Icing flashover risk assessment method for overhead transmission line in operation

Abstract

The invention discloses an icing flashover risk assessment method for an overhead transmission line in operation, and belongs to the technical field of icing flashover risk assessment. According to the method, a method of combining an AHP analytic hierarchy process and an LEC risk assessment method is adopted to establish an icing and icing flashover risk assessment model of the overhead transmission line in operation, firstly, probability influence factors of icing and icing flashover fault occurrence are determined and graded and quantified, consequence influence factors of icing and icing flashover fault occurrence are determined and graded and quantified, and the probability influence factors of icing and icing flashover fault occurrence are determined and quantified; and then determining weights of occurrence probability influence factors and occurrence consequence influence factors by adopting an AHP (Analytic Hierarchy Process), and then adopting an LEC risk assessment method. An evaluator can complete evaluation by looking up basic design conditions and line operation data of the line, the operation is simple, the technology is applied to the icing flashover risk evaluation work of the overhead transmission line in operation, and the manpower and time investment of the evaluation work can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ice flash risk assessment, and in particular to an ice flash risk assessment method for icing on an in-service overhead transmission line. Background Art

[0002] Ice flash accidents are one of the most common icing faults of overhead transmission lines. In recent years, the frequent occurrence of extreme rain, snow and freezing weather has also increased the ice flash failure rate, seriously threatening the safe operation of the power grid. Therefore, for the operating overhead transmission lines, how to effectively identify the risk of ice flash, so as to carry out targeted anti-icing and anti-icing work is an urgent problem to be solved.

[0003] The article "Risk Assessment of Transmission Network Icing Flashover Tripping during Ice Disaster Weather" proposes to establish an ice flashover status indicator for the power grid and use a fuzzy recognition method to rate the risk of predicted ice conditions, so that operation and maintenance personnel can grasp the severity and development trend of ice flashover for the power grid as a whole. This assessment method conducts risk assessment of ice flashover from the level of the power grid. It cannot conduct risk assessment for a certain line or even a certain tower. It is not targeted and the assessment method is relatively complex. The operation and maintenance management personnel are not very operational and cannot effectively guide the operation and maintenance management personnel to carry out ice flashover prevention and control work for the operating lines. At present, there is still a lack of a targeted, easy-to-operate, scientific and effective assessment method for the risk of ice flashover on operating overhead transmission lines. Summary of the invention

[0004] In view of this, the present invention aims at the deficiencies in the prior art and provides a method for assessing the ice flash risk of overhead transmission lines in operation.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for assessing the ice flash risk of icing on an in-service overhead transmission line, comprising the following steps:

[0006] S1. The LEC risk assessment method is used to establish an ice flash risk assessment model for overhead transmission lines in operation. The ice flash risk value calculation formula is as follows:

[0007] R=L×E×C (1)

[0008]

[0009] R: ice flash risk value;

[0010] L: probability of ice flash failure occurring;

[0011] E: frequency of ice flash failures;

[0012] C: Consequences of ice flash failure;

[0013] m i : The weights of the various probability influencing factors of ice-flash failure;

[0014] n i : The values ​​of the various probability influencing factors of ice-flash failure;

[0015] x i : The weights of the factors affecting the consequences of ice-flash failure;

[0016] y i : The values ​​of the factors affecting the consequences of ice-flash failure;

[0017] S2. Through analysis and investigation, determine the influencing factors of the probability of icing and ice flash failure of 7 types, assign values ​​to each probability influencing factor, use AHP hierarchical method to determine the weight coefficient, and select the value of each probability influencing factor according to the actual situation of the assessment object, so as to calculate the probability L of icing and ice flash failure;

[0018] S3. Quantify the frequency of ice flash faults by the number of ice flash faults that occur on the line or other nearby lines, and assign values ​​to the fault frequency. The frequency E of ice flash faults is determined according to the actual situation of the evaluation object.

[0019] S4. Through analysis and investigation, determine the influencing factors of the consequences of the three types of ice-covered and ice-flash faults, assign values ​​to each consequence influencing factor, use the AHP hierarchical method to determine the weight coefficient, and select the value of each consequence influencing factor according to the actual situation of the assessment object, so as to calculate the consequence impact C value of ice-covered and ice-flash faults;

[0020] S5, calculating the ice flash risk value R of the assessment object according to the L, E and C values ​​calculated in steps S2, S3 and S4 and formula (1) in step S1;

[0021] S6. According to the ice flash risk value, the ice flash risk level of the overhead transmission lines in operation is divided into the following three levels:

[0022] High risk: 40≤R≤100; Medium risk: 25≤R<40; Low risk: R<25.

[0023] Furthermore, in S2, the probability influencing factors, graded values ​​and weights of ice flash failure are as follows:

[0024]

[0025] Furthermore, in S3, the frequency classification of ice flash faults is assigned as follows:

[0026]

[0027] Furthermore, in S4, the influencing factors, graded values ​​and weights of the consequences of ice flash failure are as follows:

[0028]

[0029] Furthermore, the present invention is applicable to ice flash risk assessment of icing on operating 35 kV and above AC overhead transmission lines.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention adopts a method combining AHP analytic hierarchy process and LEC risk assessment method to establish an ice flash risk assessment model for operating overhead transmission lines. First, the probability influencing factors of ice flash failure are determined and graded and quantified, the consequence influencing factors of ice flash failure are determined and graded and quantified, and then the AHP analytic hierarchy process is used to confirm the weights of the probability influencing factors and the consequence influencing factors, and then the LEC risk assessment method is used. The assessor can complete the assessment by consulting the basic design conditions and line operation data of the line, and the operation is simple. The technology is used for the ice flash risk assessment of operating overhead transmission lines, which can effectively reduce the manpower and time investment in the assessment work.

[0032] Through this method, the icing and ice flash risks of operating overhead transmission lines can be graded, thus providing a scientific decision-making basis for the prevention and control of icing and ice flash on operating overhead transmission lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of the ice flash risk assessment method of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0035] Example 1

[0036] A method for assessing ice flash risk of operating overhead transmission lines is applicable to assessing ice flash risk of operating 35 kV and above AC overhead transmission lines. The method comprises the following steps:

[0037] S1. The LEC risk assessment method is used to establish an ice flash risk assessment model for overhead transmission lines in operation. The ice flash risk value calculation formula is as follows:

[0038] R=L×E×C (1)

[0039]

[0040] R: ice flash risk value;

[0041] L: probability of ice flash failure occurring;

[0042] E: frequency of ice flash failures;

[0043] C: Consequences of ice flash failure;

[0044] m i : The weights of the various probability influencing factors of ice-flash failure;

[0045] n i : The values ​​of the various probability influencing factors of ice-flash failure;

[0046] x i : The weights of the factors affecting the consequences of ice-flash failure;

[0047] y i : The values ​​of the factors affecting the consequences of ice-flash failure;

[0048] S2. Through analysis and investigation, determine the influencing factors of the probability of icing and ice flash failure of 7 types, assign values ​​to each probability influencing factor, use AHP hierarchical method to determine the weight coefficient, and select the value of each probability influencing factor according to the actual situation of the assessment object, so as to calculate the probability L of icing and ice flash failure;

[0049]

[0050] S3. Quantify the frequency of ice flash faults by the number of ice flash faults that occur on the line or other nearby lines, and assign values ​​to the fault frequency. The frequency E of ice flash faults is determined according to the actual situation of the evaluation object.

[0051]

[0052] S4. Through analysis and investigation, determine the influencing factors of the consequences of the three types of ice-covered and ice-flash faults, assign values ​​to each consequence influencing factor, use the AHP hierarchical method to determine the weight coefficient, and select the value of each consequence influencing factor according to the actual situation of the assessment object, so as to calculate the consequence impact C value of ice-covered and ice-flash faults;

[0053]

[0054] S5, calculating the ice flash risk value R of the assessment object according to the L, E and C values ​​calculated in steps S2, S3 and S4 and formula (1) in step S1;

[0055] S6. According to the icing and ice flash risk value, the icing and ice flash risk level of the operating overhead transmission lines is divided into the following three levels: high risk: 40≤R≤100; medium risk: 25≤R<40; low risk: R<25.

[0056] Reference Figure 1 , the specific implementation methods of the present invention are as follows:

[0057] (1) By consulting the basic design conditions and line operation data of the evaluation line, determine the design ice thickness, pollution level, insulator type, insulator structure height, insulator service life, whether micro-topography and micro-meteorology are present, the maximum ice thickness observed in history, the number of ice flashover faults in history, line voltage level, number of loops and importance, etc.

[0058] (2) The value of the designed ice thickness n1 is determined by comparing the designed ice thickness of the line with the ice thickness in the ice zone map. The ice zone map should be the ice zone map with the return period corresponding to each voltage level. The 220 kV and below lines should use the 30-year ice zone map, the 500 kV lines should use the 50-year ice zone map, and the UHV lines should use the 100-year ice zone map.

[0059] (3) Determine the pollution level factor value n2 by evaluating the pollution level of the line.

[0060] (4) Determine the insulator type factor value n3 by evaluating the line insulator type.

[0061] (5) The value of the insulator structure height factor n4 is determined by evaluating the line structure height level. The insulator structure height classification of lines of different voltage levels is shown in the following table.

[0062]

[0063] (6) Determine the value of the insulator service life factor n5 by evaluating the service life of the line insulators. The service life is calculated from the time the line is put into operation.

[0064] (7) Determine the value of micro-topography and micro-meteorological factors n by judging whether the evaluation line is located in the micro-topography and micro-meteorological zone 6. .

[0065] (8) The value of the historical maximum ice thickness factor n7 is determined by the ratio of the historical maximum ice thickness observed to the line design ice thickness. The historical maximum ice thickness observed should be the equivalent ice thickness.

[0066] (9) After determining n1, n2, n3, n4, n5, n6, and n7, use the following formula to calculate the probability L of ice flashover failure on the evaluated line.

[0067]

[0068] (10) The frequency E of ice-flashover failures on the evaluation line is determined by investigating the number of ice-flashover failures that occurred on the evaluation line or other nearby lines.

[0069] (11) Confirm the voltage level factor value y1 by evaluating the voltage level of the line.

[0070] (12) Confirm the value of the loop number factor y2 by evaluating the number of loops in the line.

[0071] (13) The importance factor value y3 is determined by judging whether the assessed line is an important transmission line or an important transmission line section.

[0072] (14) After determining y1, y2, and y3, use the following formula to calculate the impact C value of the consequences of ice flashover failure on the evaluation line.

[0073]

[0074] (15) The ice flash risk value R of the assessed line is calculated using the following formula using the L, E and C values ​​calculated in steps (9), (10) and (14).

[0075] R=L×E×C

[0076] (16) After calculating the ice flash risk value R of the assessment line, the ice flash risk level of the assessment line is determined according to the risk classification principle, where 40≤R≤100 is high risk, 25≤R<40 is medium risk, and R<25 is low risk.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art can still modify or make equivalent substitutions to the specific implementations of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A method for assessing ice flash risk of an in-service overhead transmission line, characterized in that: The following steps are involved: S1. The LEC risk assessment method is used to establish an ice flash risk assessment model for overhead transmission lines in operation. The ice flash risk value calculation formula is as follows: R=L×E×C (1) R: ice flash risk value; L: probability of ice flash failure occurring; E: frequency of ice flash failures; C: Consequences of ice flash failure; m i : The weights of the various probability influencing factors of ice-flash failure; n i : The values ​​of the various probability influencing factors of ice-flash failure; x i : The weights of the factors affecting the consequences of ice-flash failure; y i : The values ​​of the factors affecting the consequences of ice-flash failure; S2. Through analysis and investigation, determine the influencing factors of the probability of icing and ice flash failure of 7 types, assign values ​​to each probability influencing factor, use AHP hierarchical method to determine the weight coefficient, and select the value of each probability influencing factor according to the actual situation of the assessment object, so as to calculate the probability L of icing and ice flash failure; S3. Quantify the frequency of ice flash faults by the number of ice flash faults that occur on the line or other nearby lines, and assign values ​​to the fault frequency. The frequency E of ice flash faults is determined according to the actual situation of the evaluation object. S4. Through analysis and investigation, determine the influencing factors of the consequences of the three types of ice-covered and ice-flash faults, assign values ​​to each consequence influencing factor, use the AHP hierarchical method to determine the weight coefficient, and select the value of each consequence influencing factor according to the actual situation of the assessment object, so as to calculate the consequence impact C value of ice-covered and ice-flash faults; S5, calculating the ice flash risk value R of the assessment object according to the L, E and C values ​​calculated in steps S2, S3 and S4 and formula (1) in step S1; S6. According to the ice flash risk value, the ice flash risk level of the overhead transmission lines in operation is divided into the following three levels: High risk: 40≤R≤100; Medium risk: 25≤R<40; Low risk: R<25.

2. The method for assessing ice flash risk of an in-service overhead transmission line according to claim 1, characterized in that: In S2, the probability influencing factors, graded values ​​and weights of ice flash failure are as follows:

3. The method for assessing ice flash risk of an in-service overhead transmission line according to claim 1, characterized in that: In S3, the frequency classification of ice flash faults is as follows:

4. The method for assessing ice flash risk of an in-service overhead transmission line according to claim 1, characterized in that: In S4, the influencing factors, graded values ​​and weights of the consequences of ice flash failure are as follows:

5. The method for assessing ice flash risk of an in-service overhead transmission line according to claim 1, characterized in that: Applicable to the ice flash risk assessment of 35 kV and above AC overhead transmission lines in operation.

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