CN115275946A - Distribution line-oriented lightning trip probability analysis method and system - Google Patents

Abstract

The invention belongs to the field of electric power, and particularly relates to a lightning trip-out probability analysis method and system for a distribution line, wherein the method comprises the following steps: acquiring the ground flash density of a lightning area and an effective lightning receiving area of the power distribution line to determine the ground flash density of the effective lightning receiving area; calculating the flashover rate of the distribution line by using a Monte Carlo method; and obtaining the lightning trip-out probability of the distribution line according to the ground flash density, the flashover rate and the arc establishment rate of the effective lightning receiving area. Determining the ground flash density of the effective lightning receiving area by acquiring the ground flash density and the effective lightning receiving area of the distribution line; calculating the flashover rate of the distribution line by using a Monte Carlo method; according to the ground flash density, the flashover rate and the arc establishing rate of an effective lightning receiving area, obtaining the lightning trip-out probability of the distribution line; the lightning trip-out occurrence can be reasonably predicted, and lightning protection work can be guided, so that damage caused by lightning disasters is reduced.

Description

A lightning strike trip probability analysis method and system for distribution lines

technical field

The invention belongs to the field of electric power, and in particular relates to a method and system for analyzing the probability of lightning strike tripping for power distribution lines.

Background technique

Transmission lines are located in the wilderness and stretch for thousands of miles, making them vulnerable to lightning strikes. The tripping caused by the line lightning accident not only affects the normal power supply of the system, but also increases the maintenance workload of the line and switchgear, and the lightning wave will also invade the substation along the line. In recent years, great progress has been made in the lightning overvoltage and its protection of transmission lines, which provides an important basis for improving the lightning resistance level of transmission lines and ensuring the safe and reliable operation of transmission lines. But because the data of the lightning discharge process is difficult to measure accurately, the calculation results are often very different with different calculation methods. With the continuous improvement of the voltage level of transmission lines, new line structures have emerged. Judging from the actual operating experience of various countries, lightning strikes are still the main hazard to the safe and reliable operation of transmission lines.

Thunder and lightning activities are highly regional and seasonal, and lightning occurs frequently in the coastal areas of South China and East China. As the last link of power supply, the distribution network will cause equipment failure, tripping and disconnection accidents in a very short time when it is affected by lightning disasters. The operation and maintenance of the distribution network is carried out in response to the impact of lightning disasters, resulting in power outage losses and equipment losses caused by lightning disasters that cannot be resolved through effective measures, resulting in serious economic losses.

Contents of the invention

In order to solve or improve the above-mentioned problems, the present invention provides a lightning strike trip probability analysis method and system for distribution lines, and the specific technical solutions are as follows:

The present invention provides a lightning strike trip probability analysis method for distribution lines, comprising: obtaining the ground flash density in the lightning area and the effective lightning receiving area of the distribution line, so as to determine the ground flash density in the effective lightning receiving area; Calculating the flashover rate of the distribution line by Monte Carlo method; obtaining the lightning trip probability of the distribution line according to the ground flash density in the effective lightning receiving area, the flashover rate and the arc establishment rate.

Preferably, the calculation of the flashover rate of the distribution line using the Monte Carlo method includes: obtaining random variables corresponding to lightning parameters, the lightning parameters including lightning current polarity, lightning strike position, lightning strike line position, lightning current The amplitude and the instantaneous value of the industrial frequency power supply; according to the preset voltage calculation model, determine the overvoltage of the distribution line; according to the random variable and the overvoltage, obtain the flashover rate of the distribution line.

Preferably, the lightning trip probability of the distribution line is obtained according to the ground flash density, the flashover rate and the arc establishment rate of the effective lightning receiving area, including:

；其中，Ng为所述雷电区域的地闪密度，S为引起线路跳闸的所述有效受雷区域，ξ为所述闪络率，σ为所述建弧率。Lightning trip probability

; Wherein, Ng is the ground flash density of the lightning area, S is the effective lightning receiving area that causes line tripping, ξ is the flashover rate, and σ is the arc establishment rate.

Preferably, the method further includes: determining a trip warning level according to the lightning trip probability, and the warning level includes low level, middle level and high level.

Preferably, the method further includes: determining the effective lightning-stricken area where the lightning trip probability is greater than an early warning threshold, and generating corresponding early warning information.

The present invention provides a lightning strike tripping probability analysis system for distribution lines, including: a first unit for obtaining the ground flash density of the lightning area and determining the effective lightning receiving area of the distribution line based on historical data, so as to determine the The ground flash density of the effective lightning receiving area; the second unit is used to calculate the flashover rate of the distribution line using the Monte Carlo method; the third unit is used to calculate the ground flash density according to the effective lightning receiving area, The flashover rate and the arc establishment rate are used to obtain the lightning tripping probability of the distribution line.

Preferably, the calculation of the flashover rate of the distribution line using the Monte Carlo method includes: obtaining random variables corresponding to lightning parameters, the lightning parameters including lightning current polarity, lightning strike position, lightning strike line position, lightning current The amplitude and the instantaneous value of the industrial frequency power supply; according to the preset voltage calculation model, determine the overvoltage of the distribution line; according to the random variable and the overvoltage, obtain the flashover rate of the distribution line.

Preferably, the lightning trip probability of the distribution line is obtained according to the ground flash density, the flashover rate and the arc establishment rate of the effective lightning receiving area, including:

；其中，Ng为所述雷电区域的地闪密度，S为引起线路跳闸的所述有效受雷区域，ξ为所述闪络率，σ为所述建弧率。Lightning trip probability

; Wherein, Ng is the ground flash density of the lightning area, S is the effective lightning receiving area that causes line tripping, ξ is the flashover rate, and σ is the arc establishment rate.

Preferably, the system further includes: a fourth unit, configured to determine a trip warning level according to the lightning trip probability, and the warning level includes low level, middle level and high level.

Preferably, the system further includes: a fifth unit, configured to determine the effective lightning-stricken area where the lightning tripping probability is greater than an early warning threshold, and generate corresponding early warning information.

The beneficial effects of the present invention are: by obtaining the ground flash density and the effective lightning receiving area of the distribution line, to determine the ground flash density of the effective lightning receiving area; using the Monte Carlo method to calculate the flashover rate of the distribution line; according to the effective lightning receiving area The ground flash density, flashover rate and arc building rate of the lightning area can be used to obtain the lightning trip probability of the distribution line; the occurrence of lightning trip can be reasonably predicted, and the lightning protection work can be guided to reduce damage caused by lightning disasters.

Description of drawings

Fig. 1 is the schematic diagram according to the method for analyzing the probability of lightning tripping of power distribution lines according to the present invention;

Fig. 2 is a schematic diagram of a lightning trip probability analysis system for distribution lines according to the present invention.

Explanation of main reference signs:

1-first unit, 2-second unit, 3-third unit.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

It should be understood that when used in this specification and the appended claims, the terms "comprising" and "comprises" indicate the presence of described features, integers, steps, operations, elements and/or components, but do not exclude one or Presence or addition of multiple other features, integers, steps, operations, elements, components and/or collections thereof.

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

It should also be further understood that the term "and/or" used in the description of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations .

Studies have shown that the tripping of the line due to lightning strikes needs to meet: ①The overvoltage caused by the lightning strike is greater than the lightning impulse withstand voltage value U50% of the insulator, and an impact flashover occurs; ②After the lightning disappears, the impact flashover develops into a short-circuit current arc and persists , which in turn causes the relay protection device to operate and the line to trip. The line lightning resistance level and grounding mode are two important factors affecting the line trip probability. In addition, they are also closely related to the frequency of local lightning activities.

In order to solve or improve the lightning tripping preprocessing problem, a kind of distribution line-oriented lightning tripping probability analysis method as shown in Fig. mine area, to determine the ground flash density of the effective mine receiving area, S2, utilize the Monte Carlo method to calculate the flashover rate of the distribution line; S3, according to the ground flash density of the effective mine receiving area, the The flashover rate and the arc establishment rate are used to obtain the lightning tripping probability of the distribution line.

By obtaining the lightning parameters and according to the lightning parameters, the ground flash density in the lightning area is obtained, and based on the historical lightning detection information of the distribution line, the effective lightning receiving area of the distribution line is determined. Among them, the lightning parameter is the recorded lightning event occurrence information, which may include the place of occurrence, lightning density, frequency, physical properties of lightning itself, and so on. Lightning is the main fault type that causes transmission line tripping, and the development of transmission line lightning protection depends on a sound lightning risk assessment system. At present, the main indicator for evaluating the lightning risk of transmission lines is the lightning trip probability. Therefore, accurate calculation of the lightning trip probability is of great significance for the safe and stable operation of transmission lines. The lightning parameter is an indispensable and important basic parameter in calculating the lightning trip probability of a transmission line. In this embodiment, it mainly includes three aspects: the ground flash density, the probability density function of the lightning current amplitude and the lightning current waveform. Through the data of these three aspects, it can be Obtain the ground flash density of the lightning area.

The ground flash density is the matching record of the number of lightning strikes or discharge phenomena in its airspace within a certain period of time in an area and the corresponding affected area. The effective lightning receiving area of the distribution line is the area where the abnormality of the distribution line is caused by the lightning strike or the discharge phenomenon. Through the ground flash density of the lightning area and the effective lightning receiving area, the ground flash density of the area where the distribution line will be abnormal due to lightning strike/discharge can be calculated. By excluding areas not affected by lightning strikes, the accuracy of subsequent calculation of lightning strike trip probability can be improved.

The flashover rate of distribution lines is calculated by Monte Carlo method, and the arc establishment rate of distribution lines is determined. The Monte Carlo method is a stochastic simulation method, specifically a computational method based on probability and statistical theoretical methods, which uses random numbers (or more commonly pseudo-random numbers) to solve many computational problems, specifically Connect the problem to be solved with a certain probability model, and use an electronic computer to realize statistical simulation or sampling to obtain an approximate solution to the problem. The reason for adopting this method is that the lightning strike event itself is a random event, and the Monte Carlo method is more appropriate.

According to the ground flash density in the effective lightning area, the flashover rate and the arc establishment rate of the distribution line, the lightning trip probability of the distribution line is obtained. Through three important calculation parameters: ground flash density, flashover rate and arc establishment rate, the lightning trip probability is analyzed, so as to predict and analyze the cumulative trip probability, improve the prediction accuracy of the cumulative trip probability, and guide the lightning protection work. To reduce damage caused by lightning strikes. Among them, the arc establishment rate η depends on the average working voltage gradient E along the insulator string or the air gap, and is also related to the instantaneous value of the power frequency voltage at the moment of flashover and the deionization condition. The arc establishment rate is calculated by the following method: η=( 4.5×E0.75-14)*10-2, where E is the average voltage gradient of the insulator string.

The calculation of the flashover rate of the distribution line using the Monte Carlo method includes: obtaining random variables corresponding to lightning parameters, the lightning parameters including lightning current polarity, lightning strike position, lightning strike line position, lightning current amplitude and The instantaneous value of the power frequency power supply; according to the preset voltage calculation model, determine the overvoltage of the distribution line; according to the random variable and the overvoltage, obtain the flashover rate of the distribution line.

Overvoltage refers to the long-term voltage fluctuation phenomenon that the RMS value of AC voltage rises under power frequency, exceeds 10% of the rated value, and lasts for more than 1 minute; the appearance of overvoltage is usually the result of the moment of load switching. Occurs when inductive or capacitive loads are switched on or off during normal use. The overvoltage calculation model can be a lightning strike channel model or a coupling model of the electromagnetic field generated by the lightning strike to the overhead line.

According to the ground flash density, the flashover rate and the arc establishment rate of the effective lightning receiving area, the lightning tripping probability of the distribution line is obtained, including:

；其中，Ng为所述雷电区域的地闪密度，S为引起线路跳闸的所述有效受雷区域，ξ为所述闪络率，σ为所述建弧率。Lightning trip probability

; Wherein, Ng is the ground flash density of the lightning area, S is the effective lightning receiving area that causes line tripping, ξ is the flashover rate, and σ is the arc establishment rate.

η is the lightning strike trip probability; Ng is the ground flash density, which indicates the intensity of lightning activity, which is only related to the characteristics of lightning activity itself; S is the effective lightning receiving area that causes line tripping, generally within the range of 0.5km from one side of the line; ξ It is the probability of insulator flashover caused by lightning strike in the effective area, which is mainly related to the lightning withstand level of the line (related to the tower structure, grounding resistance, whether there is lightning protection line erected, insulator type, etc.), the magnitude of lightning current, and the location of lightning strike, etc., which is recorded as flashover The connection rate, σ is the arc construction rate, which is related to the structure of the tower itself and the grounding method.

From the above analysis, it can be seen that the ground flash density, lightning current magnitude, lightning strike location, grounding resistance, tower structure, etc. will affect the lightning trip probability. From a statistical point of view, it can be divided into deterministic factors (such as grounding resistance, span, insulator type, etc.) and uncertain factors (lightning current amplitude, number of lightning strikes, lightning strike points, etc.). Among them, the uncertain factors are obtained according to the statistical analysis of the characteristics of lightning activities to obtain the statistical values of relevant lightning parameters and the probability distribution model, and the Monte Carlo method is used to calculate the flashover rate. This embodiment intends to propose an improved lightning trip probability calculation method based on lightning activity characteristics on the basis of using the Monte Carlo method to calculate the trip probability, wherein the Monte Carlo method is also called a statistical simulation method and a statistical test method. It is a numerical simulation method that takes probabilistic phenomena as the research object. It is a calculation method that obtains statistical values according to the sampling survey method to estimate unknown characteristic quantities. Monte Carlo is a famous casino in Monaco, and the law is named to indicate its random sampling nature. Therefore, it is suitable for calculation and simulation experiments of discrete systems. In computational simulation, the random characteristics of the system can be simulated by constructing a probability model similar to the performance of the system and conducting random experiments on a digital computer.

The method further includes: determining a trip warning level according to the lightning trip probability, and the warning level includes a low level, a middle level and a high level.

The warning levels of lightning trip probability are divided into low level, medium level and high level. The higher the probability of lightning tripping, the higher the corresponding warning level. Early warning can be issued by means of alarm and indicator light, or can be sent to the mobile terminal of the relevant personnel on duty. Send a reminder.

The method further includes: determining the effective lightning-stricken area where the lightning trip probability is greater than an early warning threshold, and generating corresponding early warning information.

The early warning threshold can be the probability value of a certain area calculated according to the historical lightning trip data, and the early warning threshold can be different in different areas.

The present invention provides a lightning trip probability analysis system for distribution lines, including: a first unit 1, used to obtain the ground flash density of the lightning area and determine the effective lightning receiving area of the distribution line based on historical data, so as to determine The ground flash density of the effective lightning receiving area; the second unit 2 is used to calculate the flashover rate of the distribution line using the Monte Carlo method; the third unit 3 is used to The flash density, the flashover rate and the arc establishment rate are used to obtain the lightning tripping probability of the distribution line.

The system can perform specific lightning trip preprocessing procedures:

Step 1: Obtain the lightning parameters and obtain the ground flash density in the lightning area according to the lightning parameters;

Step 2: Calculating the flashover rate of distribution lines by Monte Carlo method;

Step 3: Determine the arc establishment rate of the distribution line;

Step 4: Determine the effective lightning receiving area of the distribution line based on the historical lightning detection information of the distribution line;

Step 5: Obtain the lightning strike trip probability of the distribution line according to the ground flash density of the effective lightning receiving area, the flashover rate and the arc establishment rate of the distribution line.

The calculation of the flashover rate of the distribution line using the Monte Carlo method includes: obtaining random variables corresponding to lightning parameters, the lightning parameters including lightning current polarity, lightning strike position, lightning strike line position, lightning current amplitude and The instantaneous value of the power frequency power supply; according to the preset voltage calculation model, determine the overvoltage of the distribution line; according to the random variable and the overvoltage, obtain the flashover rate of the distribution line.

According to the ground flash density, the flashover rate and the arc establishment rate of the effective lightning receiving area, the lightning tripping probability of the distribution line is obtained, including:

；其中，Ng为所述雷电区域的地闪密度，S为引起线路跳闸的所述有效受雷区域，ξ为所述闪络率，σ为所述建弧率。Lightning trip probability

; Wherein, Ng is the ground flash density of the lightning area, S is the effective lightning receiving area that causes line tripping, ξ is the flashover rate, and σ is the arc establishment rate.

The system also includes: a fourth unit, configured to determine a trip warning level according to the lightning trip probability, and the warning level includes low level, middle level and high level.

The system further includes: a fifth unit, configured to determine the effective lightning-stricken area where the lightning trip probability is greater than an early warning threshold, and generate corresponding early warning information.

Those of ordinary skill in the art can realize that the units of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software In the above description, the composition of each example has been generally described in terms of functions. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

In the embodiments provided in this application, it should be understood that the division of units is only a logical function division, and there may be other division methods in actual implementation, for example, multiple units can be combined into one unit, and one unit can be dismantled Divided into multiple units, or some features can be ignored, etc.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. All of them should be covered by the scope of the claims and description of the present invention.

Claims (10)

1. A lightning trip probability analysis method for power distribution lines, characterized in that it comprises: Obtain the ground flash density of the lightning area and the effective lightning receiving area of the distribution line to determine the ground flash density of the effective lightning receiving area; Utilize the Monte Carlo method to calculate the flashover rate of the distribution line; According to the ground flash density in the effective lightning receiving area, the flashover rate and the arc establishment rate, the lightning strike trip probability of the distribution line is obtained. 2. according to claim 1, face the lightning strike trip probability analysis method of distribution line, it is characterized in that, described utilize Monte Carlo method to calculate the flashover rate of described distribution line, comprising: Acquiring random variables corresponding to lightning parameters, said lightning parameters including lightning current polarity, lightning strike position, lightning strike line position, lightning current amplitude and instantaneous value of industrial frequency power supply; determining the overvoltage of the distribution line according to a preset voltage calculation model; According to the random variable and the overvoltage, the flashover rate of the distribution line is obtained. 3. according to the described lightning trip probability analysis method facing power distribution line of claim 1, it is characterized in that, described according to the ground flash density of described effective lightning receiving area, described flashover rate and described arc building rate, obtain The lightning trip probability of the distribution line includes: Lightning trip probability

; Wherein, Ng is the ground flash density of the lightning area, S is the effective lightning receiving area that causes line tripping, ξ is the flashover rate, and σ is the arc establishment rate. 4. according to claim 1, face the lightning strike tripping probability analysis method of distribution line, it is characterized in that, method also comprises: A trip warning level is determined according to the lightning trip probability, and the warning level includes a low level, a medium level and a high level. 5. according to claim 1, is characterized in that, method also comprises: Determining the effective lightning-stricken area in which the lightning trip probability is greater than an early warning threshold, and generating corresponding early warning information. 6. A lightning trip probability analysis system for power distribution lines, characterized in that it comprises: The first unit is used to obtain the ground flash density of the lightning area and determine the effective lightning receiving area of the distribution line based on historical data, so as to determine the ground flash density of the effective lightning receiving area; The second unit is used to calculate the flashover rate of the distribution line by using the Monte Carlo method; The third unit is configured to obtain the lightning strike trip probability of the distribution line according to the ground flash density, the flashover rate, and the arc establishment rate of the effective lightning receiving area. 7. The lightning trip probability analysis system facing distribution lines according to claim 6, wherein the calculation of the flashover rate of the distribution lines using the Monte Carlo method comprises: Acquiring random variables corresponding to lightning parameters, said lightning parameters including lightning current polarity, lightning strike position, lightning strike line position, lightning current amplitude and instantaneous value of industrial frequency power supply; determining the overvoltage of the distribution line according to a preset voltage calculation model; According to the random variable and the overvoltage, the flashover rate of the distribution line is obtained. 8. according to the described lightning strike tripping probability analysis system facing power distribution line of claim 6, it is characterized in that, described according to the ground flash density of described effective lightning receiving area, described flashover rate and described arc building rate, obtain The lightning trip probability of the distribution line includes: Lightning trip probability

; Wherein, Ng is the ground flash density of the lightning area, S is the effective lightning receiving area that causes line tripping, ξ is the flashover rate, and σ is the arc establishment rate. 9. The lightning trip probability analysis system facing distribution lines according to claim 6, wherein the system also includes: The fourth unit is configured to determine a trip warning level according to the lightning trip probability, and the warning level includes a low level, a medium level and a high level. 10. The lightning trip probability analysis system facing distribution lines according to claim 6, wherein the system also includes: The fifth unit is configured to determine the effective lightning-stricken area where the lightning trip probability is greater than the warning threshold, and generate corresponding warning information.

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