A method for calculating the pole striking rate of transmission lines without lightning arresters in heavy icing areas

Abstract

The present invention discloses a method for calculating the pole striking rate of a transmission line without a lightning arrester in a heavily icing area, the steps of which are: 1) obtaining relevant parameters of the transmission line in the heavily icing area; 2) dividing the heavily icing area into a plurality of sub-areas according to the relevant parameters of the transmission line in the heavily icing area; 3) respectively calculating the striking distances of a pole tower (1), the earth and a conductor (2); 4) determining the lightning attracting surface of the pole tower (1), the earth and the conductor (2); 5) calculating the average pole striking rate of the transmission line in each sub-area. The present invention links the lightning current amplitude with the pole striking rate. On the premise of in-depth research on the discharge characteristics of lightning, relying on the lightning strike data of actual lines, the striking distance is calculated through the principle of electrical geometry model to obtain the lightning attracting area of ​​the pole tower and the conductor. The pole striking rate obtained in this way is more in line with the change of the actual line, and can more accurately calculate the pole striking rate of the transmission line in the case of canceling the lightning arrester in the heavily icing area in the mountainous area.

Description

Technical Field

[0001] The invention relates to the field of lightning strike risk assessment for power transmission lines, in particular to a method for calculating the pole strike rate of power transmission lines without lightning arresters in areas with heavy ice. Background Art

[0002] The pole strike rate of a transmission line directly affects the accuracy of the results when calculating the lightning trip rate of the line. The pole strike rate refers to the proportion of the number of times lightning strikes the top of the pole tower to the number of times the line is struck by lightning, that is, the probability of hitting the pole tower in a lightning strike line. It is usually calculated according to the data given in the regulations. For example: in mountainous areas, the pole strike rate of a line with a single lightning conductor is 1 / 3, and the pole strike rate of a line with two lightning conductors is 1 / 4. The counter-trip rate of the line calculated according to the recommended value is often not consistent with the operating experience. More importantly, the regulatory method is not applicable to transmission lines in mountainous areas where the lightning conductor is cancelled due to the problem of heavy ice. Therefore, the traditional recommended values ​​based on low-voltage operating experience can no longer meet the needs of diversified lightning protection performance evaluation, and new methods must be adopted to calculate transmission lines without lightning conductors. Summary of the invention

[0003] The object of the present invention is to provide a method for calculating the pole striking rate of a power transmission line without a lightning arrester in a heavy ice area, comprising the following steps:

[0004] 1) Obtain relevant parameters of transmission lines in areas with heavy icing.

[0005] Transmission lines in areas with heavy icing do not include lightning arresters.

[0006] The parameters related to power transmission lines in heavy icing areas include electrical parameters and line area lightning parameters. The electrical parameters include tower height, tower head geometry, conductor height, line span, and line sag.

[0007] The line area lightning parameters include historical lightning current monitoring data.

[0008] 2) According to the relevant parameters of the transmission lines in the heavy icing area, the heavy icing area is divided into several sub-areas.

[0009] The steps to divide the heavy ice area into several sub-areas include:

[0010] 2.1) Set several lightning current ranges.

[0011] 2.2) Determine the lightning current historical monitoring data belonging to the same lightning current interval, and classify the transmission lines corresponding to these lightning current historical monitoring data into the same sub-area.

[0012] 3) Calculate the striking distances of the tower, the earth and the conductor respectively.

[0013] The strike distances are as follows:

[0014]

[0015] In the formula, R is the striking distance between the tower and the conductor; h is the height of the ground structure, including the tower height and the conductor height; R e is the earth strike distance, and K is the earth strike distance coefficient.

[0016] 4) Determine the lightning induction surfaces of poles, towers, earth and conductors.

[0017] The lightning attracting surface of the pole tower is a spherical surface with the pole tower vertex as the center and the pole tower strike distance as the radius. The lightning attracting surface of the conductor is a cylindrical surface with the conductor as the axis and the strike distance as the radius. The lightning attracting surface of the earth is a plane parallel to the earth and the distance from the ground is equal to the strike distance of the earth.

[0018] 5) Calculate the average pole striking rate of transmission lines in each sub-region.

[0019] Among them, the strike rate when the lightning current amplitude is I is as follows:

[0020] g(I)=S G / (S G +S B ) (2)

[0021] Where g(I) represents the lightning current strike rate when the lightning current amplitude is I. G , S B They represent the lightning induction surface areas of poles and towers and conductors respectively.

[0022] Different regions have different pole-beating rates. The average pole-beating rate of transmission lines in the i-th sub-region is as follows:

[0023]

[0024] In the formula, g i is the average pole striking rate of the transmission lines in the ith sub-area. mid，i is the critical lightning current amplitude corresponding to the rod striking rate of 100% in the i-th sub-area. g(I) represents the rod striking rate when the lightning current amplitude is I. f i (I) represents the probability distribution density of lightning current amplitude in the ith sub-region. i = 1, 2, ..., n; n is the total number of sub-regions divided according to the probability distribution of lightning current amplitude in actual lightning strike data in a transmission line.

[0025] The technical effect of the present invention is unquestionable. Since the pole striking rate is a function of the lightning current amplitude, the present invention proposes a method for calculating the pole striking rate of a transmission line without a lightning conductor based on the basic principle of the electrical geometry model, thereby calculating the pole striking rate of the line using the striking distance method. The present invention fully takes into account the correlation between the pole striking rate and the lightning current. Compared with the traditional procedure method, the results obtained by the present invention are more accurate and reliable. The present invention links the lightning current amplitude with the pole striking rate. On the premise of in-depth research on the discharge characteristics of lightning, relying on the lightning strike data of the actual line, the striking distance is calculated through the principle of the electrical geometry model to obtain the lightning attracting area of ​​the pole tower and the conductor. The pole striking rate obtained in this way is more in line with the changes in the actual line, and can more accurately calculate the pole striking rate of the transmission line when the lightning conductor is cancelled in the mountainous area with heavy ice. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a three-dimensional model of the lightning induction surface of the line;

[0027] Figure 2 This is a schematic diagram of the tower lightning induction surface taking into account the earth lightning induction surface;

[0028] Figure 3 The schematic diagram of the conductor lightning conducting surface considering the earth lightning conducting surface;

[0029] Figure 4 It is a cross-sectional view along the wire direction;

[0030] In the figure: pole tower 1, conductor 2, pole tower lightning induction surface 3, conductor lightning induction surface 4, earth lightning induction surface 5. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0032] Embodiment 1:

[0033] See also Figure 1 , Figure 2 , Figure 3 and Figure 4 A method for calculating the pole striking rate of a transmission line without a lightning arrester in a heavy ice area comprises the following steps:

[0034] 1) Obtain relevant parameters of transmission lines in areas with heavy icing.

[0035] Transmission lines in areas with heavy icing do not include lightning arresters.

[0036] The parameters related to power transmission lines in heavy icing areas include electrical parameters and line area lightning parameters. The electrical parameters include tower height, tower head geometry, conductor height, line span, and line sag.

[0037] The line area lightning parameters include historical lightning current monitoring data.

[0038] 2) Divide the heavily icing area into at least one sub-area based on the relevant parameters of the transmission lines in the heavily icing area.

[0039] The steps to divide the heavy ice area into several sub-areas include:

[0040] 2.1) Set several lightning current ranges.

[0041] 2.2) Determine the lightning current historical monitoring data belonging to the same lightning current interval, and classify the transmission line ranges corresponding to these lightning current historical monitoring data into the same sub-area.

[0042] 3) Calculate the striking distances of tower 1, earth and conductor 2 respectively.

[0043] The strike distances are as follows:

[0044]

[0045] In the formula, R is the striking distance between the tower and the conductor; h is the height of the ground structure, including the tower height and the conductor height; R e is the earth strike distance, and K is the earth strike distance coefficient.

[0046] 4) Determine the lightning induction surfaces of poles, towers, earth and conductors.

[0047] The pole tower lightning attracting surface 3 is a spherical surface with the pole tower vertex as the center and the pole tower strike distance as the radius; the conductor lightning attracting surface 4 is a cylindrical surface with the conductor 2 as the axis and the strike distance as the radius; the earth lightning attracting surface 5 is a plane parallel to the earth and the distance from the ground is equal to the earth strike distance.

[0048] 5) Calculate the average pole striking rate of transmission lines in each sub-region.

[0049] Among them, the strike rate when the lightning current amplitude is I is as follows:

[0050] g(I)=S G / (S G +S B ) (2)

[0051] Where g(I) represents the lightning current strike rate when the lightning current amplitude is I. G , S B They respectively represent the areas of the tower lightning induction surface 3 and the conductor lightning induction surface 4.

[0052] Different regions have different pole-beating rates. The average pole-beating rate of transmission lines in the i-th sub-region is as follows:

[0053]

[0054] In the formula, g i is the average pole striking rate of the transmission lines in the ith sub-area. mid，i is the critical lightning current amplitude corresponding to the rod striking rate of 100% in the i-th sub-area. g(I) represents the rod striking rate when the lightning current amplitude is I. f i (I) represents the probability distribution density of lightning current amplitude in the ith sub-area. i = 1, 2, ..., n. n is the total number of sub-areas divided according to the probability distribution of lightning current amplitude in the actual lightning strike data in a transmission line.

[0055] Embodiment 2:

[0056] See also Figure 1 , Figure 2 , Figure 3 and Figure 4 A method for calculating the pole striking rate of a transmission line without a lightning arrester in a heavy ice area comprises the following steps:

[0057] 1) Obtain relevant parameters of transmission lines in areas with heavy icing.

[0058] Transmission lines in areas with heavy icing do not include lightning arresters.

[0059] The parameters related to power transmission lines in heavy icing areas include electrical parameters and line area lightning parameters. The electrical parameters include tower height, tower head geometry, conductor height, line span, and line sag.

[0060] The line area lightning parameters include historical lightning current monitoring data.

[0061] 2) Calculate the striking distances of tower 1, earth and conductor 2 respectively.

[0062] The strike distances are as follows:

[0063]

[0064] In the formula, R is the striking distance between the tower and the conductor; h is the height of the ground structure, including the tower height and the conductor height; R e is the earth strike distance, and K is the earth strike distance coefficient.

[0065] 3) Determine the lightning induction surfaces of poles, towers, earth and conductors.

[0066] The pole tower lightning attracting surface 3 is a spherical surface with the pole tower vertex as the center and the pole tower strike distance as the radius; the conductor lightning attracting surface 4 is a cylindrical surface with the conductor 2 as the axis and the strike distance as the radius; the earth lightning attracting surface 5 is a plane parallel to the earth and the distance from the ground is equal to the earth strike distance.

[0067] 4) Calculate the average pole striking rate of the transmission line.

[0068] Among them, the strike rate when the lightning current amplitude is I is as follows:

[0069] g(I)=S G / (S G +S B ) (2)

[0070] Where g(I) represents the lightning current strike rate when the lightning current amplitude is I. G , S B They respectively represent the areas of the tower lightning induction surface 3 and the conductor lightning induction surface 4.

[0071] Different regions have different pole-beating rates. The average pole-beating rate of transmission lines in the i-th sub-region is as follows:

[0072]

[0073] In the formula, g i is the average pole striking rate of the transmission line. mid，i is the critical lightning current amplitude corresponding to the rod striking rate of 100%. g(I) represents the rod striking rate when the lightning current amplitude is I. i (I) represents the probability distribution density of lightning current amplitude.

[0074] Embodiment 3:

[0075] See also Figure 1 , Figure 2 , Figure 3 and Figure 4 A method for calculating the pole striking rate of a transmission line without a lightning arrester in a heavy ice area comprises the following steps:

[0076] 1) Transmission lines in heavily icing areas are remodeled by removing lightning arresters and obtaining relevant parameters of the remodeled lines.

[0077] 2) Calculate the striking distances of the tower, the earth and the conductor in sequence.

[0078] 3) According to the obtained parameters such as tower height and span, and the striking distance of each object, a perfect geometric model is established. The lightning attracting surface area of ​​the tower and the lightning attracting surface area of ​​the line in the model are calculated respectively.

[0079] 4) Calculate the pole striking rate, which is the ratio of the lightning attracting surface area of ​​the pole tower to the total lightning attracting area within a single span.

[0080] 5) Use statistical methods to obtain the lightning data of the line and obtain the probability distribution of lightning current amplitude.

[0081] 6) Change the lightning current amplitude, that is, change the striking distance of the object, and the calculated striking rate will also change accordingly. Record the critical lightning current amplitude I corresponding to the striking rate of 100% mid , the rod striking rate considering the probability distribution of lightning current amplitude is integrated.

[0082] Embodiment 4:

[0083] See also Figure 1 , Figure 2 , Figure 3 and Figure 4 Taking the actual single-span transmission line without lightning arrester as the research object, under the premise of canceling the lightning arrester, a method for calculating the pole striking rate of the transmission line without lightning arrester in the heavy ice area is proposed, which includes the following steps:

[0084] 1) Obtain relevant parameters. Obtain relevant electrical parameters of the transmission line after removing the lightning arrester and lightning parameters in the line area, including tower height, tower head geometry, conductor height, line span, sag and lightning current amplitude probability distribution.

[0085] 2) According to the strike distance calculation formula, the strike distances of the tower, conductor and earth are obtained respectively. According to theoretical research and experiments, the strike distance and lightning current amplitude have the following relationship: R = 0.67h 0.6 I 0.74 .

[0086] 3) Based on the striking distance of each object and the line-related parameters in steps 1 and 2, establish the following according to the principle of electrical geometry model: Figure 1 The three-dimensional model for calculating the pole strike rate is shown in the figure. According to the idea of ​​the electrical geometry model, when the lightning current is I, the striking distances of the pole tower, conductor and earth are fixed, where the pole tower lightning attracting surface is a sphere with the pole tower vertex as the center and the pole tower striking distance as the radius. The conductor lightning attracting surface is a cylinder with the conductor as the axis and the striking distance as the radius. Finally, it is also necessary to consider the shielding effect of the earth's lightning attracting surface on the pole tower and conductor lightning attracting surface. The earth's lightning attracting surface is a plane parallel to the earth and its distance from the ground is equal to the earth's striking distance.

[0087] 4) Determine the rod strike rate. In the calculation model, a specific lightning current amplitude corresponds to a specific lightning induction area. Therefore, the rod strike rate can be equivalent to the proportion of the number of lightning strikes on the spherical surface to the total number of lightning strikes on the line. g = S G / (S G +S B ), where S G is the lightning attracting surface area of ​​the tower, S B It is the lightning induction surface area of ​​the conductor.

[0088] 5) Based on the actual lightning monitoring data collected over a period of time, the transmission lines with large differences in lightning parameters are first divided into different areas, and the lightning current accumulation probability formulas for different areas are obtained, and then the lightning current amplitude probability density distribution f in the corresponding area of ​​the transmission line is obtained. 1 (I)...f n (I).

[0089] 6) Calculation of average pole striking rate. The pole striking rate in step 4 is calculated under a certain lightning current amplitude, that is, the pole striking rate is a function of the lightning current amplitude. As the lightning current amplitude increases, all lightning will strike the pole tower, and the pole striking rate g = 1. Suppose this critical lightning current amplitude is I mid , the pole striking rate under a certain lightning current amplitude is g(I), combined with the lightning current amplitude probability distribution density f(I) obtained in step 5, the pole striking rate calculation formula considering the lightning current amplitude probability distribution of the line is as follows:

[0090]

[0091] The pole striking rate obtained by this formula is the average pole striking rate of the transmission line. According to the different areas divided by the actual lightning strike data in step 5, each area has a pole striking rate, and different intervals of a transmission line correspond to pole striking rates g 1 ... n The present invention is based on actual lightning strike data and takes the strike distance method as the core. Compared with the recommended value of the regulation method, the strike rate obtained by this method is more in line with objective reality.

Claims

1. A method for calculating the pole striking rate of power transmission lines without lightning arresters in heavy icing areas, characterized in that: The following steps are involved: 1) Obtain relevant parameters of power transmission lines in heavy icing areas; 2) Divide the heavy icing area into several sub-areas according to the relevant parameters of the transmission lines in the heavy icing area; 3) Calculate the striking distances of the tower (1), the earth and the conductor (2) respectively; 4) Determine the lightning induction surfaces of the tower (1), the earth and the conductor (2); 5) Calculate the average pole striking rate of transmission lines in each sub-region; The strike rate when the lightning current amplitude is I is as follows: g(I)=S G (S G +S B ) (1) Where g(I) represents the lightning current amplitude I when the rod strike rate; S G , S B Respectively represent the areas of the tower lightning induction surface (3) and the conductor lightning induction surface (4); Different regions have different pole-beating rates. The average pole-beating rate of transmission lines in the i-th sub-region is as follows: In the formula, g i is the average pole striking rate of the transmission lines in the ith sub-area; mid，i is the critical lightning current amplitude corresponding to the rod striking rate of 100% in the i-th sub-area; g(I) represents the rod striking rate when the lightning current amplitude is I; f i (I) represents the probability distribution density of lightning current amplitude in the i-th sub-area; i=1, 2, ..., n; n is the total number of sub-areas divided according to the probability distribution of lightning current amplitude in actual lightning strike data in a transmission line.

2. The method for calculating the pole striking rate of power transmission lines without lightning arresters in heavy ice areas according to claim 1 is characterized in that: Transmission lines in areas with heavy icing do not include lightning arresters.

3. The method for calculating the pole striking rate of power transmission lines without lightning arresters in heavy ice areas according to claim 1 is characterized in that: The relevant parameters of power transmission lines in heavy icing areas include electrical parameters and line area lightning parameters; the electrical parameters include tower height, tower head geometry, conductor height, line span, and line sag; The line area lightning parameters include historical lightning current monitoring data.

4. A method for calculating the pole striking rate of power transmission lines without lightning arresters in heavy ice areas according to claim 3, characterized in that: The steps to divide the heavy ice area into several sub-areas include: 1) Set several lightning current intervals; 2) Determine the lightning current historical monitoring data belonging to the same lightning current interval, and classify the transmission lines corresponding to these lightning current historical monitoring data into the same sub-area.

5. The method for calculating the pole striking rate of power transmission lines without lightning arresters in heavy ice areas according to claim 1 is characterized in that: The strike distances are as follows: In the formula, R is the striking distance between the tower and the conductor; h is the height of the ground structure, including the tower height and the conductor height; R e is the earth strike distance, K is the earth strike distance coefficient; I is the lightning current amplitude.

6. The method for calculating the pole striking rate of power transmission lines without lightning arresters in heavy ice areas according to claim 1 is characterized in that: The pole tower lightning attracting surface (3) is a spherical surface with the pole tower vertex as the center and the pole tower striking distance as the radius; the conductor lightning attracting surface (4) is a cylindrical surface with the conductor (2) as the axis and the striking distance as the radius; the earth lightning attracting surface is a plane parallel to the earth and the distance from the ground is equal to the earth striking distance.

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