Quantitative evaluation method and device for safety degree of overhead transmission line channel, terminal and medium

Abstract

The invention discloses an overhead transmission line channel safety degree quantitative evaluation method and device, a terminal and a medium. The method comprises the following steps: establishing a three-level physical system model of an overhead transmission line channel; performing system failure analysis based on the three-level physical system model of the overhead transmission line channel, and establishing an overall failure model of the overhead transmission line channel; and establishing an overhead transmission line channel safety degree evaluation model based on the overall failure analysis model of the overhead transmission line channel, and performing quantitative evaluation on the safety degree of the to-be-evaluated overhead transmission line channel by using the overhead transmission line channel safety degree evaluation model. According to the method, the influence of failure and damage of different elements in the overhead transmission channel and cascade failure of multiple lines on safe and stable operation of the whole channel is considered, and the safety degree of the overhead transmission line channel can be accurately evaluated, so that more reliable scientific basis and technical support are provided for safe operation and maintenance management of a power grid.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission line channel safety assessment, and specifically designs a method, device, terminal and medium for quantitatively assessing the safety of an overhead power transmission line channel. Background Art

[0002] Overhead transmission line channel refers to an important transmission channel section consisting of two or more UHV transmission lines with small gaps between adjacent lines. As a key infrastructure system in the power system, it plays a vital role in ensuring the safe and stable operation of the entire power grid. Transmission line channels often contain multiple UHV transmission lines within a narrow channel range, and each transmission line contains a large number of structural and electrical components. There is a mutual dependence between the components and between the subsystems. Under the action of external loads, the damage of a single component may cause a failure of the transmission line, thereby affecting the normal operation of the entire overhead transmission line channel. Due to the large power transmission capacity of the overhead transmission line channel, it bears the heavy responsibility of cross-regional power supply and is the lifeline of the safe operation of the entire power grid. Once an accident occurs, it will have a huge impact on the safe operation of the entire power grid, and even cause a large-scale power outage, bringing unpredictable consequences to social security and stability, economic development and people's lives.

[0003] At present, there is limited research on overhead transmission line channels at home and abroad. The dense distribution of transmission lines and small line spacing in the channel make it more vulnerable to extreme weather and natural disasters, which directly affects the safety of the entire channel. In addition, there is a lack of research on the mutual influence between lines in the channel, the coupled common cause failure of transmission lines, and the impact and influence of different failure conditions on the entire system.

[0004] Therefore, it is necessary to carry out quantitative assessment research on the safety of overhead transmission line channels, comprehensively consider the mutual influence between multiple transmission lines in the channel, analyze the different failure modes and failure probabilities of each component and their impact on the overall safety of the channel, explore the impact of line faults in the channel on the safe and stable operation of the system, and establish a quantitative assessment model for the safety of transmission line channels to provide more reliable scientific basis and technical support for the safe operation and maintenance management of the power grid. Summary of the invention

[0005] The present invention provides a method, device, terminal and medium for quantitative safety assessment of an overhead transmission line channel, which realizes accurate assessment of the safety of an overhead transmission line channel through three aspects: physical system modeling of the overhead transmission line channel, system failure analysis of the overhead transmission line channel and quantitative safety assessment of the overhead transmission line channel.

[0006] In a first aspect, the present invention provides a method for quantitatively evaluating the safety of an overhead transmission line channel, comprising the following steps:

[0007] Establish a three-level physical system model of overhead transmission line channels;

[0008] Based on the three-level physical system model of the overhead transmission line channel, the system failure analysis is carried out and the overall failure model of the overhead transmission line channel is established;

[0009] Based on the overall failure analysis model of the overhead transmission line channel, an overhead transmission line channel safety assessment model is established, and the overhead transmission line channel safety assessment model is used to quantitatively assess the safety of the overhead transmission line channel to be assessed.

[0010] Furthermore, in the three-level physical system model of the overhead transmission line channel, the first level is the line element level, which is composed of elements or substructures in the transmission line; the second level is the transmission line level, which is composed of a single overhead transmission line in the overhead transmission line channel; the third level is the overhead transmission line channel level, which is composed of the entire overhead transmission line channel composed of multiple transmission lines of different voltage levels.

[0011] Furthermore, the specific steps of establishing the overall failure model of the overhead transmission line channel are as follows:

[0012] Failure analysis is performed on each component at the line component level in the three-level physical system model of the overhead transmission line channel, and the component vulnerability curve is obtained based on the structural disaster vulnerability analysis method;

[0013] Perform failure analysis on each line at the transmission line level in the three-level physical system model of the overhead transmission line channel, and establish an overhead transmission line failure probability model based on component fragility curves;

[0014] The channel cascading failure analysis of the overhead transmission line channel layer in the three-level physical system model of the overhead transmission line channel is carried out, and the cascading failure fault probability model of the transmission line channel considering the influence of the coupling effect of different overhead transmission lines is established;

[0015] Based on the cascading failure probability model of the transmission line channel, an overall failure model of the overhead transmission line channel is established.

[0016] Furthermore, the process of obtaining the component fragility curve is as follows:

[0017] Establish a finite element model of the transmission tower-line system in the overhead transmission line channel;

[0018] Conduct nonlinear static pushover analysis on the established transmission tower-line system finite element model, calculate the Pushover curve of the transmission tower, and determine the performance level limit LS of the tower and conductor;

[0019] Select appropriate random variable parameters, generate multiple groups of uncertainty structure samples based on Latin hypercube sampling, and establish multiple transmission tower line system uncertainty finite element models;

[0020] Taking the basic wind speed as the load intensity index, the wind load on the transmission tower line structure under different wind speeds is calculated, and multiple transmission tower line system uncertainty finite element models and wind loads of different intensities are combined to generate multiple groups of structure-wind speed analysis samples;

[0021] Finite element analysis is performed on all structure-wind speed analysis samples to obtain the corresponding maximum values ​​of conductor tension and tower top displacement;

[0022] Statistical regression analysis is performed on the structural response data to obtain the statistical fitting parameters of the probabilistic wind disaster demand model of the transmission tower line system;

[0023] Calculate the failure probability of the transmission tower system structure response exceeding a certain performance level under different wind speeds;

[0024] Draw the wind disaster vulnerability curve of the line components of the transmission tower-line system.

[0025] Furthermore, the failure probability of the transmission tower line system structure response exceeding a certain performance level under the action of different wind speeds is calculated using a wind disaster vulnerability function, and the mathematical expression of the wind disaster vulnerability function is:

[0026]

[0027] Among them, P f is the wind disaster vulnerability function, Ф(·) is the standard normal distribution function; a, b and c are statistical fitting parameters obtained by statistical regression analysis; v is the wind load intensity; LS is the performance level limit of the component; STD is the logarithmic standard deviation reflecting the degree of dispersion of the statistical regression analysis.

[0028] Furthermore, the mathematical expression of the overhead transmission line fault probability model is:

[0029]

[0030] Among them, p m (v) is the basic wind speed V r When the wind load intensity is equal to v, the failure probability of the mth overhead transmission line; n c1 and n c2They represent the number of transmission towers and the number of conductors in the mth overhead transmission line respectively; m,i is the probability of failure of the ith tower in the overhead transmission line, p m,j It represents the failure probability of the jth conductor in the overhead transmission line.

[0031] Furthermore, the mathematical expression of the overhead transmission line fault probability model is:

[0032] P Jk+2 (XYZ)=P Jk (X)+[1-P(X)]×[λ1P(Y)+λ2P(Z)-λ1λ2P(Y)P(Z)],

[0033] Among them, P Jk+2 (XYZ) is the transmission line channel set J k+2 The probability of cascading failure; P Jk (X) is the transmission line channel set J k The failure probability under the action of natural disaster H; P(Y) is the transmission line channel set J k Tightly coupled overhead transmission lines k+1 Fault under natural disaster H; P(Z) is the set of transmission line channels J k Generally coupled overhead transmission lines k+2 The failure probability under natural disaster H; λ1 and λ2 are the failure probability of the tightly coupled transmission line l k+1 、Generally coupled transmission lines k+2 For transmission line access road J k is a quantitative indicator of the degree of influence, and 0≤λ2≤λ1≤1.

[0034] Furthermore, the mathematical expression of the overhead transmission line channel safety assessment model is:

[0035] S M =1-P(J M ),

[0036] Where M is the number of transmission lines included in the overhead transmission line channel to be evaluated; P(J M ) is an overhead transmission line channel J containing M overhead transmission lines M probability of failure.

[0037] Furthermore, the specific process of using the overhead transmission line channel safety assessment model to quantitatively assess the safety of the overhead transmission line channel to be assessed is as follows:

[0038] Step S1: Collect overhead transmission line channel set J M Basic information of various components of M overhead transmission lines;

[0039] Step S2: Calculate the minimum and maximum spacing d between any two adjacent overhead transmission lines in the overhead transmission line channel. i,min and d i,max , where i∈[1,2,…,M-1];

[0040] Step S3, simulating the loads on each component in the overhead transmission line channel under the action of disaster H;

[0041] Step S4: using a structural disaster vulnerability analysis method to draw a vulnerability curve of a component, thereby calculating the failure probability of different components in each overhead transmission line under a certain load intensity;

[0042] Step S5, let i=2, take overhead transmission line channel J M The minimum center distance min(d i,min ) of two overhead transmission lines l1 and l2, forming an overhead transmission line channel set J i ;

[0043] Step S6: Calculate the overhead transmission line channel set J according to the overhead transmission line fault probability model i The failure probability P Ji ;

[0044] Step S7: Calculate the overhead transmission line channel J containing i overhead transmission lines using the overhead transmission line channel safety assessment model. i Safety S i ;

[0045] Step S8: Determine whether i is equal to M. If so, output the overhead transmission line channel J. M Safety S M , otherwise let i=i+1 and proceed to the next step;

[0046] Step S9: Determine the transmission line 1 i With channel set J i-1 The coupling relationship of the overhead transmission line is considered by using the cascading failure probability model of the transmission line channel to calculate the fault probability of the overhead transmission line l i The set of transmission line channels affected by coupling J i The probability of cascading failure P Ji ;

[0047] Step S10, return to step S7 to loop.

[0048] In a second aspect, the present invention provides a device for quantitatively evaluating the safety of an overhead power transmission line channel, comprising:

[0049] A physical system model building module is used to build a three-level physical system model of the overhead transmission line channel;

[0050] System failure analysis module, used to perform system failure analysis on the three-level physical system model of the overhead transmission line channel and establish an overall failure model of the overhead transmission line channel;

[0051] A safety evaluation model building module is used to build a safety evaluation model for an overhead transmission line channel according to an overall failure analysis model of the overhead transmission line channel;

[0052] A quantitative assessment module, used to quantitatively assess the safety of the overhead transmission line channel to be assessed using an overhead transmission line channel safety assessment model;

[0053] The evaluation result output module is used to output the safety quantitative evaluation results of the overhead transmission line channel.

[0054] Furthermore, in the three-level physical system model of the overhead transmission line channel, the first level is the line element level, which is composed of elements or substructures in the transmission line; the second level is the transmission line level, which is composed of a single overhead transmission line in the overhead transmission line channel; the third level is the overhead transmission line channel level, which is composed of the entire overhead transmission line channel composed of multiple transmission lines of different voltage levels.

[0055] Furthermore, the specific steps of the overall failure model of the overhead power transmission line channel established by the system failure analysis module are as follows:

[0056] Perform failure analysis on each component at the line component level in the three-level physical system model of the overhead transmission line channel, and obtain the component vulnerability curve based on the structural disaster vulnerability analysis method;

[0057] Perform failure analysis on each line at the transmission line level in the three-level physical system model of the overhead transmission line channel, and establish an overhead transmission line failure probability model based on component fragility curves;

[0058] The channel cascading failure analysis of the overhead transmission line channel layer in the three-level physical system model of the overhead transmission line channel is carried out, and the cascading failure fault probability model of the transmission line channel considering the influence of the coupling effect of different overhead transmission lines is established;

[0059] Based on the cascading failure probability model of the transmission line channel, an overall failure model of the overhead transmission line channel is established.

[0060] Furthermore, the process of obtaining the component fragility curve is as follows:

[0061] Establish a finite element model of the transmission tower-line system in the overhead transmission line channel;

[0062] Conduct nonlinear static pushover analysis on the established transmission tower-line system finite element model, calculate the Pushover curve of the transmission tower, and determine the performance level limit LS of the tower and conductor;

[0063] Select appropriate random variable parameters, generate multiple groups of uncertainty structure samples based on Latin hypercube sampling, and establish multiple transmission tower line system uncertainty finite element models;

[0064] Taking the basic wind speed as the load intensity index, the wind load on the transmission tower line structure under different wind speeds is calculated, and multiple transmission tower line system uncertainty finite element models and wind loads of different intensities are combined to generate multiple groups of structure-wind speed analysis samples;

[0065] Finite element analysis is performed on all structure-wind speed analysis samples to obtain the corresponding maximum values ​​of conductor tension and tower top displacement;

[0066] Statistical regression analysis is performed on the structural response data to obtain the statistical fitting parameters of the probabilistic wind disaster demand model of the transmission tower line system;

[0067] The wind disaster vulnerability function is used to calculate the failure probability of the transmission tower line system structure response exceeding a certain performance level under different wind speeds. The mathematical expression of the wind disaster vulnerability function is:

[0068]

[0069] Among them, P f is the wind disaster vulnerability function, Ф(·) is the standard normal distribution function; a, b and c are statistical fitting parameters obtained by statistical regression analysis; v is the wind load intensity; LS is the performance level limit of the component; STD is the logarithmic standard deviation reflecting the degree of dispersion of statistical regression analysis;

[0070] Draw the wind disaster vulnerability curve of the line components of the transmission tower-line system.

[0071] Furthermore, the mathematical expression of the overhead transmission line fault probability model is:

[0072]

[0073] Among them, p m (v) is the basic wind speed V r When the wind load intensity is equal to v, the failure probability of the mth overhead transmission line; n c1 and n c2 They represent the number of transmission towers and the number of conductors in the mth overhead transmission line respectively; m,iis the probability of failure of the ith tower in the overhead transmission line, p m,j It represents the failure probability of the jth conductor in the overhead transmission line.

[0074] Furthermore, the mathematical expression of the cascading failure probability model of the transmission line channel is:

[0075]

[0076] Among them, P Jk+2 (XYZ) is the transmission line channel set J k+2 The probability of cascading failure; P Jk (X) is the transmission line channel set J k The failure probability under the action of natural disaster H; P(Y) is the transmission line channel set J k Tightly coupled overhead transmission lines k+1 Fault under natural disaster H; P(Z) is the set of transmission line channels J k Generally coupled overhead transmission lines k+2 The failure probability under natural disaster H; λ1 and λ2 are the failure probability of the tightly coupled transmission line l k+1 、Generally coupled transmission lines k+2 For transmission line access road J k is a quantitative indicator of the degree of influence, and 0≤λ2≤λ1≤1.

[0077] Furthermore, the mathematical expression of the overhead transmission line channel safety assessment model constructed by the safety assessment model construction module is:

[0078] S M =1-P(J M ),

[0079] Where M is the number of transmission lines included in the overhead transmission line channel to be evaluated; P(J M ) is an overhead transmission line channel J containing M overhead transmission lines M probability of failure.

[0080] Furthermore, the specific process of the quantitative assessment module using the overhead transmission line channel safety assessment model to quantitatively assess the safety of the overhead transmission line channel to be assessed is as follows:

[0081] Step S1: Collect overhead transmission line channel set J M Basic information of various components of M overhead transmission lines;

[0082] Step S2: Calculate the minimum and maximum spacing d between any two adjacent overhead transmission lines in the overhead transmission line channel. i,min and di,max , where i∈[1,2,…,M-1];

[0083] Step S3, simulating the loads on each component in the overhead transmission line channel under the action of disaster H;

[0084] Step S4: using a structural disaster vulnerability analysis method to draw a vulnerability curve of a component, thereby calculating the failure probability of different components in each overhead transmission line under a certain load intensity;

[0085] Step S5, let i=2, take overhead transmission line channel J M The minimum center distance min(d i,min ) of two overhead transmission lines l1 and l2, forming an overhead transmission line channel set J i ;

[0086] Step S6: Calculate the overhead transmission line channel set J according to the overhead transmission line fault probability model i The failure probability P Ji ;

[0087] Step S7: Calculate the overhead transmission line channel J containing i overhead transmission lines using the overhead transmission line channel safety assessment model. i Safety S i ;

[0088] Step S8: Determine whether i is equal to M. If so, output the overhead transmission line channel J. M Safety S M , otherwise let i=i+1 and proceed to the next step;

[0089] Step S9: Determine the transmission line 1 i With channel set J i-1 The coupling relationship of the overhead transmission line is considered by using the cascading failure probability model of the transmission line channel to calculate the fault probability of the overhead transmission line l i The set of transmission line channels affected by coupling J i The probability of cascading failure P Ji ;

[0090] Step S10, return to step S7 to loop.

[0091] In a third aspect, the present invention provides a computer terminal, comprising a processor, a memory and a communication interface; the memory and the communication interface are coupled to the processor, and the memory is used to store computer program instructions; wherein, when the processor executes the computer program instructions, the computer terminal implements the overall reliability assessment method as described in the first aspect above.

[0092] In a fourth aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer program instructions, and when the computer program instructions are executed by a processor, the overall reliability assessment method as described in the first aspect above is implemented.

[0093] Beneficial effects:

[0094] 1. The present invention conducts a hierarchical analysis study on a complex transmission line channel including multiple overhead transmission lines. Based on the research idea from the local to the whole, a three-level physical system model of the transmission line channel is constructed. The three levels in the overhead transmission line channel system are defined and explained respectively, and the channel system composed of different components and subsystems is decomposed, which lays a solid foundation for the reasonable analysis of the failure of the overhead transmission line channel system and the accurate evaluation of the safety performance.

[0095] 2. The present invention adopts a structural disaster vulnerability analysis method to analyze different components such as poles, towers, and conductors in the overhead transmission line channel, explores the damage mode of transmission line components under disasters, and establishes a relationship between the disaster load intensity and the component failure and damage probability, namely, the vulnerability curve. The failure probability of different components in the line under different load intensities can be obtained quickly and easily, which is helpful for evaluating the safety status of transmission line components.

[0096] 3. In view of the characteristics of dense distribution of transmission lines and small line spacing in the channel, the present invention explores the mutual influence between multiple transmission lines in the overhead transmission line channel, introduces a common cause failure model, and defines the cascading failure probability of transmission lines considering the coupling effect of different lines in the channel, providing an effective solution for the safety assessment of transmission lines considering cascading failures.

[0097] 4. The present invention innovatively proposes a quantitative assessment method for the safety of overhead transmission line channels. This method takes into account the impact of failure and damage of different components in the channel and cascading failure of multiple lines on the safe and stable operation of the entire channel, and establishes a quantitative assessment model for the safety of overhead transmission line channels, providing a more reliable scientific basis and technical support for the safe operation and maintenance management of the transmission line channel system. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Figure 1 is a flow chart of the method of the present invention;

[0099] Figure 2 is a schematic diagram of a three-level physical system model of an overhead transmission line channel;

[0100] Figure 3 It is a framework diagram for component failure analysis;

[0101] Figure 4 It is a simplified model diagram of an overhead transmission line;

[0102] Figure 5 is a schematic diagram of cascading failure of overhead transmission line channels;

[0103] Figure 6 It is a flow chart for conducting safety assessment of overhead transmission line corridors;

[0104] Figure 7 is a principle block diagram of the safety quantification assessment device of the present invention;

[0105] Figure 8 It is a principle block diagram of the computer terminal of the present invention;

[0106] Fig. 9 It is a calculation diagram of a real overhead transmission line channel;

[0107] Fig.10 It is the only Pushover curve diagram of the transmission tower;

[0108] Fig.11 It is a schematic diagram of the results of statistical regression analysis of the structural corresponding data;

[0109] Fig.12 It is a schematic diagram of the wind disaster vulnerability curve of the line components of the transmission tower line system. DETAILED DESCRIPTION

[0110] The present invention is further described below in conjunction with the embodiments and drawings. All features disclosed in all embodiments in this specification, or steps in all methods or processes disclosed implicitly, except for mutually exclusive features and / or steps, can be combined and / or expanded or replaced in any manner.

[0111] An overhead transmission line channel refers to an important transmission channel section consisting of two or more ultra-high voltage transmission lines with a small gap between adjacent lines. As a key infrastructure system in the power system, it plays a vital role in ensuring the safe and stable operation of the entire power grid. The transmission line channel often contains multiple ultra-high voltage transmission lines within a narrow channel range, and each transmission line contains a large number of structural and electrical components. There is a mutual dependence between each component and between each subsystem. Under the action of external loads, the damage of a single component may cause a transmission line failure, thereby affecting the normal operation of the entire overhead transmission line channel. Therefore, in order to accurately evaluate the safety of the overhead transmission line channel, the means adopted in this embodiment are as follows:

[0112] like Figure 1 As shown, this embodiment provides a method for quantitatively evaluating the safety of an overhead transmission line channel, and the specific steps are as follows:

[0113] Step 1: Establish a three-level physical system model of the overhead transmission line channel;

[0114] The physical system of the infrastructure is composed of different interdependent subsystems, and each subsystem is also composed of interrelated lower-level subsystems or components. Therefore, the physical performance of the infrastructure system depends largely on the joint action of all subsystems and components. For the overhead transmission line channel system, a three-level physical system can be used for modeling expression, which mainly includes the line element level, the transmission line level, and the overhead transmission line channel level.

[0115] The three-level physical system of overhead transmission line channels established in this embodiment is as follows: Figure 2 As shown, it can be seen that: the first level, that is, the line element level part, is the most basic element or substructure in the overhead transmission line channel, such as transmission towers, conductors, foundations, insulators, hardware, etc. As an indispensable component of the transmission line, these elements or substructures are directly affected by environmental loads. Their failure and damage will cause further failure of related elements or substructures in the line, directly resulting in the inability of the transmission line to transmit electric energy normally, resulting in the loss of its function. The second level, that is, the transmission line level part, is the infrastructure subsystem in the overhead transmission line channel that can independently provide functions, that is, a single transmission line in the overhead transmission line channel, which undertakes the task of long-distance, large-capacity electric energy transmission. The third level is the overhead transmission line channel level part, that is, the entire system of the overhead transmission line channel, which is composed of multiple transmission lines of different voltage levels, which jointly complete the transmission of electric energy in the area. Due to the narrow range of the transmission line channel, the failure of any transmission line may cause the failure of other transmission lines in the channel, causing a large-scale power outage.

[0116] Step 2: Perform system failure analysis based on the three-level physical system model of the overhead transmission line channel and establish an overall failure model of the overhead transmission line channel;

[0117] Failure analysis is an important basis and prerequisite for conducting quantitative safety assessment of overhead transmission line channels. Based on the three-level physical system model of the overhead transmission line channel established in step 1, when conducting overall failure analysis, the simulation starts from the failure of components in the line, and the analysis is carried out layer by layer, and finally the overall failure analysis model of the overhead transmission line channel is established. The specific steps are as follows:

[0118] Step 2.1, performing failure analysis on each component at the line component level in the three-level physical system model of the overhead transmission line channel, and obtaining a component vulnerability curve based on a structural disaster vulnerability analysis method;

[0119] Under the action of external loads, the failure of the entire overhead transmission line channel begins with the failure of some components in the line, such as the collapse of individual towers, broken wires, wind deflection flashover of insulator strings, etc. There are multiple failure modes. For ease of understanding, this embodiment mainly considers the failure of two types of components: transmission towers and wires. The reason is that once the two types of structural damage, tower collapse and wire breakage, occur, the maintenance cycle is long and the maintenance cost is high. The faulty line will be unable to provide services for a long period of time, resulting in serious power outages. The failure simulation of towers and wires adopts the structural disaster vulnerability analysis method. The concept of structural disaster vulnerability analysis was first derived from the concept of seismic vulnerability analysis, which represents the possibility of a structure reaching or exceeding a certain performance level under a certain intensity of load, and can be used to calculate the conditional probability of a structure suffering different degrees of damage such as destruction and collapse under different levels of load. In this embodiment, wind load is used as an example for explanation, and the wind disaster vulnerability analysis process of transmission line components is as follows:

[0120] 1) Component vulnerability function

[0121] The failure model of a component can be represented by a component vulnerability curve, which reflects the relationship between the probability of component failure and different load intensities. The component wind damage vulnerability function can be expressed in the following mathematical form:

[0122] P f =P(D≥LS|V r =v) (1)

[0123] Among them, the basic wind speed V r is the strength index of wind load; D is the wind disaster demand parameter; LS is the defined performance level limit; P[D>=LS|V r =v] represents the wind load intensity V r =v, the conditional failure probability when the demand parameter D reaches or exceeds its performance level limit.

[0124] For transmission towers, referring to design specifications and related research, the displacement of the top of the tower is generally used as a performance indicator. On the one hand, it corresponds to the stress state of the component as a whole and is a macroscopic manifestation of the stress change of the component; on the other hand, the use of the top displacement is also convenient for a unified and quantitative description of the strength state of the structure as a whole. For transmission wires, the damage and destruction of the structure as a whole is mainly controlled by the internal force of the wire. Once the wire reaches its rated breaking force, it loses its bearing capacity. It is more reasonable to use the wire tension as the performance indicator of the transmission wire. Therefore, this embodiment selects the top displacement u of the tower and the wire tension Q as the quantitative indicators D of the performance level of the transmission tower and the transmission wire respectively.

[0125] 2) Quantification of performance level

[0126] In order to obtain the specific expression of the component's wind disaster vulnerability function, the performance level limit LS of the component must be solved. For transmission towers, a nonlinear static pushover analysis is performed on the finite element model of the transmission tower line system in the overhead transmission line channel under a 90° wind direction angle, and the Pushover curve of the tower can be obtained. The static pushover analysis, also known as static elastoplastic analysis and pushover analysis, is used in this embodiment to evaluate the performance of the transmission tower line system under wind loads. This method applies increasing wind loads to examine the stress and deformation behavior of the structure during the entire loading process, that is, records the data of the performance indicators of the structure under each step of the load (such as the vertex displacement), thereby drawing a pushover curve (wind load-vertex displacement relationship diagram) until the ultimate failure state of the structure is reached. Parameters such as the yield point, ultimate bearing capacity and deformation capacity of the structure can be obtained through the curve.

[0127] If the inflection point in the Pushover curve is regarded as the critical collapse failure state point of the tower (i.e., the load no longer increases but the top displacement of the transmission tower increases sharply), then the top displacement of the tower corresponding to the critical collapse failure state is the performance level quantitative index limit LS under the collapse failure state of the tower structure. For the transmission line, its performance level limit LS can be taken as its line breaking tension.

[0128] 3) Probabilistic wind disaster demand analysis

[0129] The probabilistic wind disaster demand model reflects the load intensity index IM (i.e. the basic wind speed V r ) and the probability relationship between the structural wind disaster demand parameter D (i.e., conductor tension Q, tower top displacement u). Referring to the research conducted by Nielson et al., the wind disaster demand of transmission line components is related to the basic wind speed V r The relationship between can be fitted by a linear polynomial or a quadratic polynomial function, namely:

[0130] lnD=lna+blnv (2)

[0131] lnD=a(lnv) 2 +blnv+c (3)

[0132] Where a, b and c are the fitting parameters obtained from statistical regression analysis.

[0133] According to the wind load calculation formula, the wind load on the transmission line is proportional to the square of the wind speed, so the quadratic polynomial shown in formula (3) is used to describe the relationship between the wind disaster demand and the basic wind speed. In the existing wind disaster vulnerability analysis, it is usually assumed that the wind disaster demand and wind resistance of the structure obey the log-normal distribution. Therefore, the probabilistic wind disaster demand model of the transmission line element can be further rewritten as:

[0134]

[0135] Where Ф(·) is the standard normal distribution function; STD is the logarithmic standard deviation reflecting the degree of dispersion of regression analysis.

[0136] After obtaining the fitting parameters a, b and c of formula (3) through regression analysis, substitute formula (3) into formula (4), and its wind disaster vulnerability function can be finally expressed as:

[0137]

[0138] In the formula, the calculation formula of STD is as follows:

[0139]

[0140] Where D i is the maximum structural response obtained from the nonlinear time-history analysis of the i-th structure-wind speed sample; n is the total number of samples.

[0141] 4) Vulnerability analysis process

[0142] In summary, after determining the performance level limit and probability demand model of the transmission line, the structural wind disaster vulnerability analysis can be carried out according to equations (1) to (6). The analysis framework is as follows: Figure 3 As shown, the specific implementation steps are as follows:

[0143] Step A1, establishing a finite element model of a transmission tower line system in an overhead transmission line channel;

[0144] Step A2: Perform nonlinear static pushover analysis on the established transmission tower line system finite element model, calculate the Pushover curve of the transmission tower, and determine the performance level limit LS of the tower and the conductor;

[0145] Step A3, selecting appropriate random variable parameters, generating n groups of uncertainty structure samples based on Latin hypercube sampling (LHS), and establishing n transmission tower line system uncertainty finite element models described in step A1;

[0146] Step A4: Take the basic wind speed V r As the load intensity index IM, a set of wind speeds is generated every 5 m / s between 5 m / s and 40 m / s, and the wind load on the structure is calculated. The structural uncertainty finite element model is combined with wind loads of different intensities, and finally a total of 8n sets of structure-wind speed analysis samples are generated;

[0147] Step A5: Perform finite element analysis calculations on all structure-wind speed analysis samples to obtain the corresponding maximum values ​​of conductor tension Q and tower vertex displacement u;

[0148] Step A6: Perform statistical regression analysis on the structural response data according to formula (3) to obtain statistical fitting parameters a, b, c of the probabilistic wind disaster demand model of the transmission tower line system;

[0149] Step A7, calculating the failure probability of the transmission tower line system structure response exceeding a certain performance level under different wind speeds according to equations (5)-(6);

[0150] Step A8: Draw the wind disaster vulnerability curve of the line components of the transmission tower-line system.

[0151] Step 2.2, performing failure analysis on each line at the transmission line level in the three-level physical system model of the overhead transmission line channel, and establishing an overhead transmission line failure probability model based on component fragility curves;

[0152] According to the wind disaster vulnerability curve of the components in the transmission line obtained in step 2.1, a line vulnerability model reflecting the relationship between the failure probability and load intensity of the transmission line is further constructed. Any section of the transmission line can be expressed as follows Figure 4 The simplified model shown in the figure is considered as a model consisting of multiple transmission lines and multiple transmission towers in series. Assuming that the failure probability of each component in the line is independent of each other, that is, any collapse of the tower or breakage of the wire will cause the failure of the transmission line and interruption of power transmission, then when the load intensity V r =v, the fault probability model of the overhead transmission line is the calculation formula for the fault probability of the mth transmission line, which is expressed as:

[0153]

[0154] Where n c1 and n c2 They represent the number of transmission towers and conductors in the mth line respectively; p m,i is the probability of failure of the ith tower in the line, p m,j represents the failure probability of the jth conductor in the line, p m,i 、p m,j and p m are functions of the load intensity v.

[0155] Step 2.3, performing channel cascading failure analysis on the overhead transmission line channel level in the three-level physical system model of the overhead transmission line channel, and establishing a cascading failure fault probability model of the transmission line channel considering the influence of coupling effects of different overhead transmission lines;

[0156] In order to consider the mutual influence between multiple transmission lines in the channel, the concept of structural cascading failure is introduced in this embodiment. Structural cascading failure refers to the failure of related lines or other components caused by the failure of a single transmission line or a single component in the transmission line system. Structural cascading failure of the overhead transmission line channel will cause the fault to spread to a larger range and cause a large-scale power outage. Specifically, this embodiment considers the following Figure 5 Structural cascading failure of an overhead transmission line corridor shown.

[0157] Since the gap between two adjacent UHV line conductors in an overhead transmission line channel is small, the failure of a component in one line (direct failure) may affect the failure of another parallel line component in the channel (indirect failure). Figure 5 As shown in FIG. 1 , a tower in an overhead transmission line A collapses under load. If the length of the collapsed tower head and tower body is greater than or equal to the distance between the collapsed tower head and the adjacent overhead transmission line B, the components in the overhead transmission line B will be destroyed. In order to consider this cascading failure, a common cause failure model is introduced in this embodiment, and the cascading failure probability of the transmission line channel is calculated as follows:

[0158] In the overhead transmission line channel set J containing k lines k ={l1,l2,…,l k , k≥2}, the minimum and maximum distances between any two adjacent overhead transmission lines are d i,min and d i,max (i∈[1,2,…,k-1]), then the k+1th transmission line l k+1 With channel set J k The minimum and maximum spacing between k,min ,d k,max , we can judge d k,min ,d k,max The effective line distance threshold value d corresponding to a certain disaster type H H The size relationship between them determines the overhead transmission line channel set J k The coupling relationship with the k+1th line, the coupling relationship judgment criteria are as follows:

[0159] If the overhead transmission line channel set J k With transmission line k+1 If the lines are tightly coupled, the line spacing satisfies:

[0160] d k,min ≤d H (8)

[0161] If the overhead transmission line channel set J k With transmission linek+1 If the circuits are generally coupled, the circuit spacing satisfies:

[0162] d k,min <d H ≤d k,max (9)

[0163] Otherwise, the overhead transmission line channel set J k With transmission line k+1 There is no coupling relationship between them.

[0164] The preset effective line distance threshold value d H Depending on the type of disaster, the threshold value of the distance between effective lines will be different for different natural disaster types (such as lightning, wildfire, landslide, ice cover, and strong wind).

[0165] The overhead transmission line channel set J k The failure under the action of natural disaster H is recorded as event X. From formula (7), we can know that its failure probability P Jk The calculation formula of (X) is as follows:

[0166]

[0167] Where n X_1 and n X_2 is the set of channels J k The number of towers and conductors, p i 、p j is the failure probability of the i-th tower and the j-th conductor under the action of disaster H.

[0168] The transmission line channel set J k Tightly coupled transmission lines k+1 The failure under natural disaster H is recorded as event Y. From formula (7), we can know that its probability P(Y) is calculated as follows:

[0169]

[0170] Where n Y_1 and n Y_2 It is a transmission line k+1 The number of towers and conductors, p i1 、p j1 is the failure probability of the i1th tower and the j1th conductor in the line under the action of disaster H.

[0171] The transmission line channel set J k Generally coupled transmission lines k+2 The failure of the middle tower set under natural disaster H is recorded as event Z. From formula (7), we can know that its probability P(Z) is calculated as follows:

[0172]

[0173] Where n Z_1 and n Z_2 It is a transmission line k+2 The number of towers and conductors, p i2 、p j2 is the failure probability of the i2th tower and the j2th conductor in the line under the action of disaster H.

[0174] In summary, under the action of disaster H, considering line l k+1 and l k+2 Transmission line channel set J affected by different coupling effects k+2 The probability of cascading failure P Jk+2 (XYZ), that is, the transmission line channel J k+2 The probability of cascading failure P Jk+2 The calculation model of (XYZ) is expressed as:

[0175] P Jk+2 (XYZ)=P Jk (X)+[1-P(X)]×[λ1P(Y)+λ2P(Z)-λ1λ2P(Y)P(Z)] (13)

[0176] Where λ1 and λ2 are the parameters describing the tightly coupled circuit l k+1 、General coupled line k+2 For transmission line channel J k The quantitative index of the coupling or influence degree is λ1=0.8 and λ2=0.2 in this embodiment, and 0≤λ2≤λ1≤1. The quantitative index coefficient of the coupling degree can be adjusted according to empirical statistical results.

[0177] Step 2.4: Based on the cascading failure probability model of the transmission line channel, an overall failure model of the overhead transmission line channel is established.

[0178] Based on the failure analysis of overhead transmission line channels, the state of the lines in the overhead transmission line channels under disaster loads can be simulated to obtain the failure probability of the overhead transmission line considering cascading failures. Therefore, the safety assessment model of the entire overhead transmission line channel can be expressed as:

[0179] S M =1-P(J M ) (14)

[0180] Where M is the number of transmission lines contained in the overhead transmission line channel to be evaluated; P(J M ) is an overhead transmission line channel J containing M lines MThe failure probability can be calculated according to formula (13).

[0181] Step 3: Based on the overall failure analysis model of the overhead transmission line channel, an overhead transmission line channel safety assessment model is established, and the overhead transmission line channel safety assessment model is used to quantitatively assess the safety of the overhead transmission line channel to be assessed. The specific process is as follows: Figure 6 As shown:

[0182] Step S1: Collect the transmission line channel set J M Basic information of various components of M overhead transmission lines;

[0183] Step S2: Calculate the minimum and maximum distances d between any two adjacent overhead transmission lines in the channel i,min and d i,max , where i∈1,2,…,M-1;

[0184] Step S3, simulating the loads on each component in the overhead transmission line channel under the action of disaster H;

[0185] Step S4: using a structural disaster vulnerability analysis method to draw a vulnerability curve of a component, thereby calculating the failure probability of different components in each overhead transmission line under a certain load intensity;

[0186] Step S5: Since the overhead transmission line channel contains at least two overhead transmission lines, let i=2 and take the transmission line channel J. M The minimum center distance min(d i,min ) of two overhead transmission lines l1 and l2, forming a transmission line channel set J i ;

[0187] Step S6: Calculate the transmission line channel set J according to formula (7): i The failure probability P Ji ;

[0188] Step S7: Calculate the overhead transmission line channel J containing i overhead transmission lines according to formula (14): i Safety S i ;

[0189] Step S8: Determine whether i is equal to M. If so, output the overhead transmission line channel J. M Safety S M , otherwise let i=i+1 and proceed to the next step;

[0190] Step S9: Determine the overhead transmission line l according to formula (8)-formula (9) i With overhead transmission line channel collection J i-1The coupling relationship is calculated by using formula (10)-formula (13) considering the overhead transmission line l i Overhead transmission line channel set J affected by coupling i The probability of cascading failure P Ji ;

[0191] Step S10, return to step S7 to loop.

[0192] Corresponding to the overall reliability evaluation method of the embodiment of the present invention, the embodiment of the present invention may provide an overall reliability evaluation device, a terminal and a computer-readable storage medium, which are respectively as follows:

[0193] like Figure 7 As shown, this embodiment also proposes a transmission tower-line structure overall reliability assessment device based on the above-mentioned overall reliability assessment method, including:

[0194] A physical system model building module is used to build a three-level physical system model of the overhead transmission line channel. The process of building the three-level physical system model is shown in step 1.

[0195] The system failure analysis module is used to perform system failure analysis on the three-level physical system model of the overhead transmission line channel and establish an overall failure model of the overhead transmission line channel. For the establishment process of the overall failure model, please refer to the contents described in steps 2.1 to 2.4;

[0196] A safety evaluation model building module is used to build a safety evaluation model for an overhead transmission line channel according to the overall failure analysis model of the overhead transmission line channel. For the specific building process of the safety evaluation model for the overhead transmission line channel, please refer to step 3.

[0197] A quantitative assessment module is used to use an overhead transmission line channel safety assessment model to perform a quantitative assessment on the safety of the overhead transmission line channel to be assessed. For the specific process, please refer to steps S1 to S10;

[0198] The evaluation result output module is used to output the safety quantitative evaluation results of the overhead transmission line channel.

[0199] like Figure 8 As shown, this embodiment also proposes a computer terminal based on the above-mentioned overall reliability assessment method, wherein the computer terminal includes a processor, a memory and a communication interface; the memory and the communication interface are coupled to the processor, and the memory is used to store computer program instructions; wherein, when the processor executes the computer program instructions, the computer terminal implements the above-mentioned overall reliability assessment method.

[0200] An embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer program instructions, and when the computer program instructions are executed by a processor, the above-mentioned overall reliability assessment method is implemented.

[0201] Next, taking a certain overhead transmission line channel as an example, the safety assessment of the overhead transmission line channel project is carried out. This UHV overhead transmission line channel shuttles between the borders of the two provinces, passing through more than ten cities and counties along the line. The terrain of the area is mainly plains, with tidal flats, river branches, and contiguous fish ponds. The entire channel is 266.026 kilometers long, with 1,331 poles and towers, and a single line length of 970.566 kilometers, including two AC lines and four DC lines. Restricted by the planning and approval of the path corridor, the width of the transmission channel is severely limited, showing the current situation of extremely narrow channel corridors. The center pile spacing of the line is about 80-100 meters, among which: the average width of the three-line parallel section channel is 160m, and the narrowest width is 82m (center pile spacing, the narrowest channel width is 117 meters), and the average width of the four-line parallel section channel is 240m, and the narrowest width is 226m (center pile spacing, the narrowest channel width is 262 meters).

[0202] The distribution diagram of each transmission line in this channel is as follows: Fig. 9 As shown. When conducting the safety assessment of the overhead transmission line channel project, it is divided into two sections according to the number of transmission lines. Channel section I is a "three-line parallel" section consisting of line A, line B, and line C; channel section II is a "four-line parallel" section consisting of line A, line B, line C, and line D. The calculated length of each line in channel section I is 165.648km, including 324 poles and towers, the average channel width is 160m, and the average spacing between lines is 80m. The calculated length of each line in channel section II is 11.657km, including 24 poles and towers, the average channel width is 240m, and the average spacing between lines is 80m.

[0203] In order to quantify the safety of the above-mentioned overhead transmission line channel actual project, the failure scenario under wind load is simulated. First, the failure simulation of each component in the line is carried out and the failure probability is calculated. Based on the wind disaster vulnerability analysis process given in step 2.1, first, under the action of a 90° wind direction angle, a nonlinear static pushover analysis is performed on the deterministic finite element model of the transmission tower line system in the overhead transmission line channel. The Pushover curve of the transmission tower can be obtained as follows: Fig.11 As shown. Fig.11 It can be seen that when the basic wind speed reaches about 47.7m / s, the top displacement of the transmission tower increases sharply. At this time, it can be considered that it is in a critical collapse damage state. The top displacement of the tower corresponding to the critical collapse damage state is 0.948m, so it is used as the quantitative indicator limit LS of the performance level under the collapse damage state of the tower structure.

[0204] For overhead transmission lines, the performance level limit under the broken line damage state is 227.34 kN. Therefore, appropriate random variables are selected to conduct nonlinear dynamic time history analysis on the established 8×100 sets of structure-wind speed samples, and the maximum displacement u of the top of the transmission line tower of each uncertainty finite element model is extracted. i , Maximum wire tension Q i , using formula (3) to perform quadratic polynomial regression analysis on the obtained data, the final result is as follows Fig.11 As shown, where: Fig.11 (a) shows the regression analysis results of the tower top displacement. Fig.11 (b) shows the wire tension regression analysis results.

[0205] Depend on Fig.11 It can be seen that for the tower top displacement and conductor tension, the residual S obtained by using the logarithmic quadratic polynomial regression analysis is r are 2.8884 and 2.0536 respectively, which shows that the quadratic polynomial model shown in formula (3) can well reflect the basic wind speed V r Based on the fitting results, the wind disaster vulnerability functions corresponding to the damage performance levels of transmission towers and conductors can be obtained as shown in equations (15)-(16):

[0206]

[0207] Based on equations (12)-(13), the wind disaster vulnerability curves of towers and conductors are drawn, as follows: Fig.12 As shown, where: Fig.12 (a) shows the displacement fragility curve of the tower top. Fig.12 (b) shows the wire tension fragility curve.

[0208] Based on the wind damage vulnerability curve of the components, the operating status of each transmission line in the channel under the design wind speed is determined, and the safety of the entire overhead transmission line channel is evaluated. Figure 4 The simplified analysis model shown in the figure generates a set of failure probabilities of multiple lines in the channel under load, taking the effective line distance threshold value d H The value is 600m. According to equations (8)-(14), the coupling relationship between the lines in the channel is evaluated and the failure probability of the overhead transmission line channel considering cascading failure is calculated. Finally, the safety evaluation results of the two sections of the overhead transmission line channel under the design wind speed are shown in Table 1.

[0209] Table 1 Results of comprehensive quantitative assessment of overhead transmission line channel safety

[0210] Overhead transmission line channel UHV overhead transmission line channel section I UHV overhead transmission line channel section II Failure probability 0.0043 0.0004 Safety 0.9957 0.9996

[0211] In summary, this embodiment firstly carries out a hierarchical analysis study on a complex transmission line channel including multiple overhead transmission lines. According to the research idea from the local to the whole, a three-level physical system model of the transmission line channel is constructed. Then, the structural disaster vulnerability analysis method is used to analyze different components such as towers and conductors in the overhead transmission line channel, explore the damage mode of the transmission line components under the action of disasters, and establish a vulnerability curve that expresses the relationship between the disaster load intensity and the failure probability of the component. Then, the failure probability of different components in the overhead transmission line under different load intensities is obtained. Then, in view of the characteristics of dense distribution of transmission lines and small line spacing in the channel, the mutual influence between multiple transmission lines in the overhead transmission line channel is comprehensively considered, and the different failure modes and failure probabilities of each component and their influence on the overall safety of the channel are analyzed. The influence of line faults in the channel on the safe and stable operation of the system is explored, and a transmission line channel safety quantitative assessment model considering the failure and damage of different components in the channel and the influence of cascading failure of multiple lines on the safe and stable operation of the entire channel is established, which can provide more reliable scientific basis and technical support for the safe operation and maintenance management of the power grid.

[0212] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Under the guidance of the present invention, ordinary technicians in this field can make various similar expressions without violating the purpose and claims of the present invention, and such changes all fall within the scope of protection of the present invention.

Claims

1. A method for quantitatively evaluating the safety of an overhead transmission line channel, characterized in that: The steps include: Establish a three-level physical system model of overhead transmission line channels; Based on the three-level physical system model of the overhead transmission line channel, the system failure analysis is carried out and the overall failure model of the overhead transmission line channel is established; Based on the overall failure analysis model of the overhead transmission line channel, an overhead transmission line channel safety assessment model is established, and the overhead transmission line channel safety assessment model is used to quantitatively assess the safety of the overhead transmission line channel to be assessed.

2. The method for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 1, characterized in that: In the three-level physical system model of the overhead transmission line channel, the first level is the line element level, which is composed of elements or substructures in the transmission line; the second level is the transmission line level, which is composed of a single overhead transmission line in the overhead transmission line channel; the third level is the overhead transmission line channel level, which is composed of the entire overhead transmission line channel composed of multiple transmission lines of different voltage levels.

3. The method for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 1, characterized in that: The specific steps of establishing the overall failure model of the overhead transmission line channel are as follows: Failure analysis is performed on each component at the line component level in the three-level physical system model of the overhead transmission line channel, and the component vulnerability curve is obtained based on the structural disaster vulnerability analysis method; Perform failure analysis on each line at the transmission line level in the three-level physical system model of the overhead transmission line channel, and establish an overhead transmission line failure probability model based on component fragility curves; The channel cascading failure analysis of the overhead transmission line channel layer in the three-level physical system model of the overhead transmission line channel is carried out, and the cascading failure fault probability model of the transmission line channel considering the influence of the coupling effect of different overhead transmission lines is established; Based on the cascading failure probability model of the transmission line channel, an overall failure model of the overhead transmission line channel is established.

4. The method for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 3, characterized in that: The process of obtaining the component fragility curve is as follows: Establish a finite element model of the transmission tower-line system in the overhead transmission line channel; Conduct nonlinear static pushover analysis on the established transmission tower-line system finite element model, calculate the Pushover curve of the transmission tower, and determine the performance level limit LS of the tower and conductor; Select appropriate random variable parameters, generate multiple groups of uncertainty structure samples based on Latin hypercube sampling, and establish multiple transmission tower line system uncertainty finite element models; Taking the basic wind speed as the load intensity index, the wind load on the transmission tower line structure under different wind speeds is calculated, and multiple transmission tower line system uncertainty finite element models and wind loads of different intensities are combined to generate multiple groups of structure-wind speed analysis samples; Finite element analysis is performed on all structure-wind speed analysis samples to obtain the corresponding maximum values ​​of conductor tension and tower top displacement; Statistical regression analysis is performed on the structural response data to obtain the statistical fitting parameters of the probabilistic wind disaster demand model of the transmission tower line system; Calculate the failure probability of the transmission tower system structure response exceeding a certain performance level under different wind speeds; Draw the wind disaster vulnerability curve of the line components of the transmission tower-line system.

5. The method for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 4, characterized in that: The failure probability of the transmission tower line system structure response exceeding a certain performance level under different wind speeds is calculated using a wind disaster vulnerability function, and the mathematical expression of the wind disaster vulnerability function is: Among them, P f is the wind disaster vulnerability function, Ф(·) is the standard normal distribution function; a, b and c are statistical fitting parameters obtained by statistical regression analysis; v is the wind load intensity; LS is the performance level limit of the component; STD is the logarithmic standard deviation reflecting the degree of dispersion of the statistical regression analysis.

6. The method for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 3, characterized in that: The mathematical expression of the overhead transmission line fault probability model is: Among them, p m (v) is the basic wind speed V r When the wind load intensity is equal to v, the failure probability of the mth overhead transmission line; n c1 and n c2 They represent the number of transmission towers and the number of conductors in the mth overhead transmission line respectively; m,i is the probability of failure of the ith tower in the overhead transmission line, p m,j It represents the failure probability of the jth conductor in the overhead transmission line.

7. The method for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 3, characterized in that: The mathematical expression of the cascading failure probability model of the transmission line channel is: Among them, P Jk+2 (XYZ) is the transmission line channel set J k+2 The probability of cascading failure; P Jk (X) is the transmission line channel set J k The failure probability under the action of natural disaster H; P(Y) is the transmission line channel set J k Tightly coupled overhead transmission lines k+1 Fault under natural disaster H; P(Z) is the set of transmission line channels J k Generally coupled overhead transmission lines k+2 The failure probability under natural disaster H; λ1 and λ2 are the failure probability of the tightly coupled transmission line l k+1 、Generally coupled transmission lines k+2 For transmission line access road J k is a quantitative indicator of the degree of influence, and 0≤λ2≤λ1≤1.

8. The method for quantitatively assessing the safety of an overhead transmission line channel according to any one of claims 3 to 7, characterized in that: The mathematical expression of the overhead transmission line channel safety assessment model is: S M =1-P(J M ), Where M is the number of transmission lines included in the overhead transmission line channel to be evaluated; P(J M ) is an overhead transmission line channel J containing M overhead transmission lines M probability of failure.

9. The method for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 8, characterized in that: The specific process of using the overhead transmission line channel safety assessment model to quantitatively assess the safety of the overhead transmission line channel to be assessed is as follows: Step S1: Collect overhead transmission line channel set J M Basic information of various components of M overhead transmission lines; Step S2: Calculate the minimum and maximum spacing d between any two adjacent overhead transmission lines in the overhead transmission line channel. i,min and d i,max , where i∈[1,2,…,M-1]; Step S3, simulating the loads on each component in the overhead transmission line channel under the action of disaster H; Step S4: using a structural disaster vulnerability analysis method to draw a vulnerability curve of a component, thereby calculating the failure probability of different components in each overhead transmission line under a certain load intensity; Step S5, let i=2, take overhead transmission line channel J M The minimum center distance min(d i,min ) of two overhead transmission lines l1 and l2, forming an overhead transmission line channel set J i ; Step S6: Calculate the overhead transmission line channel set J according to the overhead transmission line fault probability model i The failure probability P Ji ; Step S7: Calculate the overhead transmission line channel J containing i overhead transmission lines using the overhead transmission line channel safety assessment model. i Safety S i ; Step S8: Determine whether i is equal to M. If so, output the overhead transmission line channel J. M Safety S M , otherwise let i=i+1 and proceed to the next step; Step S9: Determine the transmission line 1 i With channel set J i-1 The coupling relationship of the overhead transmission line is considered by using the cascading failure probability model of the transmission line channel to calculate the fault probability of the overhead transmission line l i The set of transmission line channels affected by coupling J i The probability of cascading failure P Ji ; Step S10, return to step S7 to loop.

10. A device for quantitatively evaluating the safety of an overhead power transmission line channel, characterized in that: include: A physical system model building module is used to build a three-level physical system model of the overhead transmission line channel; System failure analysis module, used to perform system failure analysis on the three-level physical system model of the overhead transmission line channel and establish an overall failure model of the overhead transmission line channel; A safety evaluation model building module is used to build a safety evaluation model for an overhead transmission line channel according to an overall failure analysis model of the overhead transmission line channel; A quantitative assessment module, used to quantitatively assess the safety of the overhead transmission line channel to be assessed using an overhead transmission line channel safety assessment model; The evaluation result output module is used to output the safety quantitative evaluation results of the overhead transmission line channel.

11. The device for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 10, characterized in that: In the three-level physical system model of the overhead transmission line channel, the first level is the line element level, which is composed of elements or substructures in the transmission line; the second level is the transmission line level, which is composed of a single overhead transmission line in the overhead transmission line channel; the third level is the overhead transmission line channel level, which is composed of the entire overhead transmission line channel composed of multiple transmission lines of different voltage levels.

12. The device for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 10, characterized in that: The specific steps of establishing the overall failure model of the overhead transmission line channel are as follows: Failure analysis is performed on each component at the line component level in the three-level physical system model of the overhead transmission line channel, and the component vulnerability curve is obtained based on the structural disaster vulnerability analysis method; Perform failure analysis on each line at the transmission line level in the three-level physical system model of the overhead transmission line channel, and establish an overhead transmission line failure probability model based on component fragility curves; The channel cascading failure analysis of the overhead transmission line channel layer in the three-level physical system model of the overhead transmission line channel is carried out, and the cascading failure fault probability model of the transmission line channel considering the influence of the coupling effect of different overhead transmission lines is established; Based on the cascading failure probability model of the transmission line channel, an overall failure model of the overhead transmission line channel is established.

13. The device for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 12, characterized in that: The process of obtaining the component fragility curve is as follows: Establish a finite element model of the transmission tower-line system in the overhead transmission line channel; Conduct nonlinear static pushover analysis on the established transmission tower-line system finite element model, calculate the Pushover curve of the transmission tower, and determine the performance level limit LS of the tower and conductor; Select appropriate random variable parameters, generate multiple groups of uncertainty structure samples based on Latin hypercube sampling, and establish multiple transmission tower line system uncertainty finite element models; Taking the basic wind speed as the load intensity index, the wind load on the transmission tower line structure under different wind speeds is calculated, and multiple transmission tower line system uncertainty finite element models and wind loads of different intensities are combined to generate multiple groups of structure-wind speed analysis samples; Finite element analysis is performed on all structure-wind speed analysis samples to obtain the corresponding maximum values ​​of conductor tension and tower top displacement; Statistical regression analysis is performed on the structural response data to obtain the statistical fitting parameters of the probabilistic wind disaster demand model of the transmission tower line system; The wind disaster vulnerability function is used to calculate the failure probability of the transmission tower line system structure response exceeding a certain performance level under different wind speeds. The mathematical expression of the wind disaster vulnerability function is: Among them, P f is the wind disaster vulnerability function, Ф(·) is the standard normal distribution function; a, b and c are statistical fitting parameters obtained by statistical regression analysis; v is the wind load intensity; LS is the performance level limit of the component; STD is the logarithmic standard deviation reflecting the degree of dispersion of statistical regression analysis; Draw the wind disaster vulnerability curve of the line components of the transmission tower-line system.

14. The device for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 12, characterized in that: The mathematical expression of the overhead transmission line fault probability model is: Among them, p m (v) is the basic wind speed V r When the wind load intensity is equal to v, the failure probability of the mth overhead transmission line; n c1 and n c2 They represent the number of transmission towers and the number of conductors in the mth overhead transmission line respectively; m,i is the probability of failure of the ith tower in the overhead transmission line, p m,j It represents the failure probability of the jth conductor in the overhead transmission line.

15. The device for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 12, characterized in that: The mathematical expression of the cascading failure probability model of the transmission line channel is: Among them, P Jk+2 (XYZ) is the transmission line channel set J k+2 The probability of cascading failure; P Jk (X) is the transmission line channel set J k The failure probability under the action of natural disaster H; P(Y) is the transmission line channel set J k Tightly coupled overhead transmission lines k+1 Fault under natural disaster H; P(Z) is the set of transmission line channels J k Generally coupled overhead transmission lines k+2 The failure probability under natural disaster H; λ1 and λ2 are the failure probability of the tightly coupled transmission line l k+1 、Generally coupled transmission lines k+2 For transmission line access road J k is a quantitative indicator of the degree of influence, and 0≤λ2≤λ1≤1.

16. The device for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 10, characterized in that: The mathematical expression of the overhead transmission line channel safety evaluation model constructed by the safety evaluation model construction module is: S M =1-P(J M ), Where M is the number of transmission lines included in the overhead transmission line channel to be evaluated; P(J M ) is an overhead transmission line channel J containing M overhead transmission lines M probability of failure.

17. The device for quantitatively evaluating the safety of an overhead power transmission line channel according to claim 10, characterized in that: The specific process of the quantitative assessment module using the overhead transmission line channel safety assessment model to perform quantitative assessment on the safety of the overhead transmission line channel to be assessed is as follows: Step S1: Collect overhead transmission line channel set J M Basic information of various components of M overhead transmission lines; Step S2: Calculate the minimum and maximum spacing d between any two adjacent overhead transmission lines in the overhead transmission line channel. i,min and d i,max , where i∈[1,2,…,M-1]; Step S3, simulating the loads on each component in the overhead transmission line channel under the action of disaster H; Step S4: using a structural disaster vulnerability analysis method to draw a vulnerability curve of a component, thereby calculating the failure probability of different components in each overhead transmission line under a certain load intensity; Step S5, let i=2, take overhead transmission line channel J M The minimum center distance min(d i,min ) of two overhead transmission lines l1 and l2, forming an overhead transmission line channel set J i ; Step S6: Calculate the overhead transmission line channel set J according to the overhead transmission line fault probability model i The failure probability P Ji ; Step S7: Calculate the overhead transmission line channel J containing i overhead transmission lines using the overhead transmission line channel safety assessment model. i Safety S i ; Step S8: Determine whether i is equal to M. If so, output the overhead transmission line channel J. M Safety S M , otherwise let i=i+1 and proceed to the next step; Step S9: Determine the transmission line 1 i With channel set J i-1 The coupling relationship of the overhead transmission line is considered by using the cascading failure probability model of the transmission line channel to calculate the fault probability of the overhead transmission line l i The set of transmission line channels affected by coupling J i The probability of cascading failure P Ji ; Step S10, return to step S7 to loop.

18. A computer terminal, characterized in that: The computer terminal includes a processor, a memory and a communication interface; the memory and the communication interface are coupled to the processor, and the memory is used to store computer program instructions; wherein, when the processor executes the computer program instructions, the computer terminal implements the method as described in any one of claims 1-9.

19. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer program instructions, and when the computer program instructions are executed by a processor, the method according to any one of claims 1 to 9 is implemented.

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