CN110414120B - A Calculation Method for Lightning Protection Performance of Transmission Lines Without Lightning Arrester Lines - Google Patents

Abstract

The invention provides a method for calculating lightning protection performance of a power transmission line without a lightning conductor. And calculating lightning current and overvoltage distribution when the power transmission line is struck by lightning by an electromagnetic transient calculation method. Multiple lightning strokes in the nature are equivalent to a single pulse lightning stroke through an amplitude and waveform adjusting method, and then overvoltage at two ends of the lightning arrester body and an energy absorption value of the lightning arrester are calculated to judge whether the base rod tower has flashover tripping or not, and the like, so that the lightning stroke tripping rate of the whole line is calculated. The lightning protection performance calculation method can provide guidance and suggestion for research and development and configuration of a lightning protection device for canceling a lightning conductor line, so that lightning trip-out rate parameters in the lightning protection performance can be obtained more accurately and reliably.

Description

A Calculation Method of Lightning Protection Performance of Transmission Lines Without Lightning Arrester Lines

technical field

The invention belongs to the field of on-line monitoring of electric power systems, and in particular relates to a calculation method for lightning protection performance of transmission lines without lightning protection lines.

Background technique

According to statistics, more than 50% of the tripping accidents in the power system are caused by lightning strikes. With the continuous development of the economy, the people have put forward higher requirements for the reliability of electricity consumption, reducing the lightning tripping rate of transmission lines, and establishing and improving the lightning protection of the power grid. The system plays an important role in improving the stability of the power system.

The calculation of lightning protection performance of transmission lines is the basis of line lightning protection transformation, and has very important guiding significance for the development and configuration of lightning protection devices. In recent years, the number of lines that cancel the lightning protection line and install lightning protection measures such as lightning arresters with gaps and synthetic insulators for lightning protection and ice flashing has gradually increased. Lightning energy withstand capability of arrester under multiple lightning effects. Therefore, how to evaluate the lightning protection capability of the transmission line without the lightning protection line remains to be further studied.

In view of the above situation, it is urgent to design a calculation or design method for the lightning protection performance of the transmission line without the lightning protection line, so as to provide guidance and suggestions for the research and development and configuration of the lightning protection device without the lightning protection line.

Contents of the invention

Since the existing lightning protection performance calculation method is mainly aimed at transmission lines with lightning protection lines, and does not take into account the influence of lightning arrester flow capacity on transmission line lightning protection capabilities, the present invention proposes a calculation method for lightning protection performance of transmission lines without lightning protection lines The method aims to provide guidance and suggestions for the development and configuration of lightning protection devices that cancel the lightning protection line, so as to obtain the lightning tripping rate parameters in lightning protection performance more accurately and reliably.

According to one aspect of the present invention, there is provided a method for calculating the lightning protection performance of a transmission line without a lightning conductor, the steps of which include the following steps 1 to 4:

Step 1: Calculate the lightning activity characteristics of the entire line according to the procedure method and statistical method. The parameters of the lightning activity characteristics include the line lightning density N(I), the lightning current amplitude probability distribution P(I), and according to the line lightning density N (1) calculate and obtain the line lightning number of times σ of the transmission line of every 100km;

Step 2: Establish an electromagnetic transient simulation model, calculate the lightning current and overvoltage distribution characteristics of the transmission line under different lightning strike conditions, and combine the lightning current amplitude probability distribution P(I) related to the lightning current to obtain the energy absorbed by the arrester E;

Step 3: According to the insulator design parameters of the arrester, the energy absorption capacity E ₀ of the arrester is calculated. Under different lightning strike conditions, the lightning withstand level E _L0 of the transmission line is obtained by judging whether the energy E absorbed by the arrester is greater than or equal to the energy absorption capacity E ₀ of the arrester , the lightning withstand level E _L0 of the transmission line is the corresponding lightning current energy value when the arrester absorbs energy E to E0 _;

Step 4: According to the lightning energy E _L , the probability distribution of lightning current amplitude P(I), the number of lightning strikes on the line σ, and the lightning resistance level E _L0 of the transmission line, calculate the lightning trip rate q of the transmission line with a length of 100 km, where q is calculated as :

q＝P(E _L )×σ

Among them, the lightning current energy E _L is related to the lightning current amplitude probability distribution P(I), and P(E _L ) represents the probability that the lightning current energy E _L exceeds the lightning withstand level E _L0 ; after obtaining the lightning trip rate q, according to each The lightning tripping rate q of 100km is used to calculate the lightning tripping rate of the entire line.

Further, said step 1 also includes:

The calculation formula of described lightning current amplitude probability distribution P (I) is:

Among them, a represents the average value of the line lightning current amplitude, b represents the probability distribution index, the values of a and b are determined by the lightning current wave head time and wave tail time, and the independent variable I represents the lightning current amplitude.

Further, in the step 1, according to the line lightning density N (I), the line lightning times σ of the transmission line of every 100km specifically includes:

The number of lightning strikes on the line is calculated by the lightning strike density of the transmission corridor and the lightning strike width Y per 1 km. The formula for the strike strike width Y of the line is:

Y=4h+b

Among them, Y represents the width of lightning, h represents the average width of the wire, and b represents the distance of the outermost wire;

The formula for the number of lightning strikes σ on the line is:

σ＝N(I)*100*Y

Wherein, the number of lightning strikes on the line σ is a floating-point number with decimals.

Further, the calculation method of the energy E absorbed by the arrester in the step 2 is:

Through the simulation calculation of the electromagnetic transient simulation model, the overvoltage at both ends of the arrester and the lightning current waveform flowing through the arrester are obtained. The energy E absorbed by the arrester is determined by the following formula:

When E exceeds the energy absorption capacity E0 of the arrester, it is considered that a tripping accident has occurred on the transmission line, where u(t) and i(t) represent the lightning overvoltage and lightning current at both ends of the arrester, t represents time, T represents the lightning action time, E Indicates the energy absorbed by the arrester, where the lightning current i(t) at both ends of the arrester is related to the probability distribution P(I) of the amplitude of the lightning current.

Further, in the calculation method of the energy E absorbed by the arrester in the step 2, the following equivalent calculation method of multiple lightning and single lightning is used: the amplitude and wave head time of the equivalent single lightning wave are equal to the multiple lightning current The amplitude of the first lightning pulse current and the wave head time, the total charge of the equivalent single lightning wave and the total charge of multiple lightning waves are equal, and then determine the wave tail time of the equivalent single lightning wave.

Further, the equivalent calculation method of multiple mines and single mines also includes:

The tail time t _R and the total charge Q _eq of the equivalent single lightning current can be approximately equivalent to the following formula:

In the above formula, T represents the lightning action time, and I _eq is the amplitude of the equivalent single lightning.

Further, the step 4 also includes: the calculation formula of the lightning energy _EL is specifically:

Among them, p(I) represents the lightning overcurrent distribution function closely related to the lightning current amplitude probability distribution P(I), u _L (t) represents the overvoltage generated by the lightning current on the transmission line, and T represents the lightning action time.

In another aspect, the present invention also discloses a calculation device for lightning protection performance of a transmission line without a lightning conductor, including:

at least one processor; and

at least one memory communicatively coupled to the processor, wherein:

The memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the lightning protection performance calculation method described in any one of the above.

In another aspect, the present invention also discloses a non-transitory computer-readable storage medium, the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the computer described in any one of the above. The lightning protection performance calculation method described above.

The idea of the technical solution of the present invention is that according to the specific structural design of the transmission line and the tower, the number of lightning strikes along the corridor of the transmission line is calculated by the procedure method and the statistical method. The distribution of lightning current and overvoltage when the transmission line is struck by lightning is calculated by the electromagnetic transient calculation method. By adjusting the amplitude and waveform, the multiple lightning strikes in nature are equivalent to a single pulse lightning strike, and then calculate the overvoltage at both ends of the arrester body and the energy absorption value of the arrester to judge whether the base tower has a flashover trip, and so on, the calculation is Lightning trip rate of the entire line.

Compared with the prior art, the beneficial effect of the present invention is that the method of the present invention is used in the setting calculation of lightning protection performance parameters of transmission lines, and the influence of multiple lightnings on the lightning resistance level of transmission lines is considered. Compared with the traditional lightning protection performance setting calculation method, the invention can more accurately evaluate the lightning protection performance of the transmission line without the lightning protection line, and then guide the configuration and installation of the lightning protection equipment for the transmission line.

Description of drawings

Fig. 1 is the flow chart of canceling ground wire transmission line lightning protection performance calculation method among the present invention;

Fig. 2 is a curve diagram of the probability distribution curve of the lightning current amplitude of a typical ground wire transmission line;

Fig. 3 is the schematic diagram of transmission line lightning strike electromagnetic transient simulation model in the present invention;

Fig. 4 is a schematic diagram of an equivalent method between multiple lightning strikes and single lightning strikes in the present invention.

detailed description

The present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments, and the technical problems and beneficial effects solved by the technical solutions of the present invention are also described. It should be pointed out that the described embodiments are only intended to facilitate the implementation of the present invention understood without any limitation.

As shown in Fig. 1, the flow chart of calculation method of lightning protection performance of transmission line without lightning protection line (ground wire) can be used to calculate the calculation method of lightning protection performance of the entire line through the lightning tripping rate of each section of line. Taking 100km as the unit, the calculation method steps of the lightning protection performance of every 100km subsection of the entire line include the following steps 1 to 4:

Step 1: Calculate the lightning activity characteristics of the entire line according to the procedure method and statistical method. The parameters of the lightning activity characteristics include the line lightning density N(I) and the lightning current amplitude probability distribution P(I), and calculate according to the line lightning density Obtain the number of line lightning strikes per 100km transmission line σ;

Step 2: Establish an electromagnetic transient simulation model, calculate the distribution characteristics of the lightning current and overvoltage of the transmission line under different lightning strike conditions, and combine the lightning current amplitude probability distribution P(I) related to the lightning current to obtain the lightning arrester absorption Energy E;

Step 3: According to the insulator design parameters of the arrester, the energy absorption capacity E ₀ of the arrester is calculated. Under different lightning strike conditions, the lightning withstand level E _L0 of the transmission line is obtained by judging whether the energy E absorbed by the arrester is greater than or equal to the energy absorption capacity E ₀ of the arrester , the lightning withstand level E _L0 of the transmission line is the corresponding lightning current energy value when the arrester absorbs energy E to E0 _;

Step 4: According to the lightning energy E _L , the probability distribution of lightning current amplitude P(I), the number of lightning strikes on the line σ, and the lightning resistance level E _L0 of the transmission line, calculate the lightning trip rate q of the transmission line with a length of 100 km, where q is calculated as :

q＝P(E _L )×σ

Among them, the lightning current energy E _L is related to the probability distribution of lightning current amplitude P(I), and P(E _L ) represents the probability that the lightning current energy E _L exceeds the lightning withstand level E _L0 . After obtaining the lightning trip rate q, it can be calculated according to each The lightning tripping rate q of 100km is used to calculate the lightning tripping rate of the entire line.

It should be pointed out that, from the formula of q in step 4, it can be seen that the lightning trip rate q is the number of trips per year on a transmission line with a length of 100 km (it can be a floating point number), that is, the lightning current energy within the range of lightning induced by the transmission line The number of times E _L exceeds the lightning withstand level E _L0 of the transmission line.

Further, when the lightning energy E _L is greater than E _L0 , it can be known that a tripping accident occurs on the transmission line, because E _L is closely related to the lightning current amplitude probability distribution P(I), preferably, in order to make the calculation of the lightning energy E _L more accurate To be precise, the calculation formula of E _L is:

Among them, p(I) represents the lightning overcurrent distribution function closely related to the lightning current amplitude probability distribution P(I), and u _L (t) represents the overvoltage generated by lightning current on the transmission line.

The lightning current amplitude probability distribution curve shown in Figure 2, according to the specific shape of the transmission line and the tower, through the procedure method and statistical method, the lightning current amplitude and the number of lightning strikes in the corridor area of the transmission line without the lightning protection line are counted, and the obtained The formula of the lightning density along the line and the probability distribution P(I) of the lightning current amplitude along the line is shown in the following formula:

Among them, a represents the average value of the line lightning current amplitude, b represents the probability distribution index, the values of a and b are determined by the lightning current wave head time and wave tail time, and the independent variable I represents the lightning current amplitude, specifically, for For every 100km transmission line without lightning protection line, the lightning current waveform can preferably be a double-exponential waveform with a wave head time of 2.6 μs and a wave tail time of 50 μs.

In addition, the number of lightning strikes on the line can be calculated by the lightning strike density of the transmission corridor and the lightning strike width Y per 1 km. The calculation method of the strike strike width Y is as follows:

Y=4h+b

Among them, Y represents the width of the lightning, h represents the average width of the wire, and b represents the distance of the outermost wire.

The number of lightning strikes on the line σ is equal to the lightning strike density N(I) multiplied by the lightning induced width Y multiplied by the line length. When calculating the lightning strike trip rate, the line length is 100km, so the line length here is 100km. In addition, it can be seen from step 1 that the lightning strike density N (1) Determined by statistical data, the formula for the number of lightning strikes σ on the line is as follows:

σ＝N(I)*100*Y

Wherein, the number of lightning strikes on the line σ may be a floating-point number with decimals, so as to represent the number of lightning strikes per 100km in a theoretical statistical sense.

Figure 3 shows the electromagnetic transient simulation calculation model of the transmission line, in which the multi-wave impedance model is used for the transmission line and the tower. Compared with the traditional line modeling method, the grounded lightning protection line is cancelled. The horizontal line in Fig. 3 is the power transmission line, and the vertical line and the box represent the tower, because the insulator model has nothing to do with the lightning tripping rate studied in the present invention, and the insulator and the tower model are too detailed, so detailed modeling is not carried out in the present invention Explain and label.

In step 2, the overvoltage at both ends of the arrester and the lightning current waveform flowing through the arrester can be obtained through simulation calculations. The energy E absorbed by the arrester can be determined by the following formula: when E exceeds the energy absorption capacity E ₀ of the arrester, it is considered that the transmission line has Trip accident:

Among them, u(t) and i(t) respectively represent the lightning overvoltage and lightning current at both ends of the arrester, t represents time, T represents the lightning action time, E represents the energy absorbed by the arrester, and the lightning current i(t) at both ends of the arrester Because it is mainly affected by the probability distribution of lightning current amplitude P(I) (since the relationship between i(t) and P(I) during a lightning strike belongs to the basic knowledge in the field of electric disaster prevention and mitigation, so it will not be repeated here), the arrester The absorbed energy E is also closely related to the probability distribution P(I) of the lightning current amplitude.

Since the actual lightning strike environment is more prone to frequent continuous multiple lightning strikes in a short period of time, in order to make the calculation of the energy E absorbed by the arrester calculated by the electromagnetic transient simulation calculation model in step 2 more accurate under different lightning strike conditions , the present invention additionally designs an equivalent calculation method for multiple mines and single mines to improve calculation efficiency. In addition, when judging whether the transmission line of the lightning protection line is canceled for flashover and tripping, the amplitude of the lightning current plays a decisive factor when calculating the overvoltage at both ends of the arrester body. When calculating the energy of the lightning current, it is necessary to consider the influence of multiple lightnings. It is necessary to calculate the multiple lightning equivalent to a single lightning wave.

Specifically, Fig. 4 shows the equivalent calculation method of multiple lightning and single lightning. Statistical data indicate that in reality, most lightning currents are multiple lightning waves, that is, there are multiple pulse lightning currents during a lightning strike. For the convenience of calculation, multiple lightning strikes can be equivalent to a single lightning wave for calculation. The equivalent principle is: a single-pulse lightning strike is a double-exponential waveform, and the amplitude and rise time of a single-pulse lightning strike are the same as the first pulse of a multi-pulse lightning strike. Ray is equal. The tail time of an equivalent single-pulse lightning strike is determined by the number and energy of multiple lightning strikes. The principle of equivalence is that the charge of an equivalent single mine is equal to the total charge of multiple mines. For example, there are three lightning pulses in a lightning strike process. For the convenience of calculation, the three pulse lightning pulses in the multiple lightning strike process are equivalent to a single pulse lightning. The total charge Q _eq of the equivalent single lightning current is equal to the sum of the three pulse lightning charges Q1, Q2, Q3 in the multiple lightning.

Therefore, it can be seen that the specific equivalent calculation method is: the amplitude and wave head time of the equivalent single lightning wave are equal to the amplitude and wave head time of the first lightning pulse current in the multiple lightning currents. The total charge of the equivalent single lightning wave is equal to the total charge of multiple lightning waves, thus determining the tail time of the equivalent single lightning wave.

The amplitude I _eq of the equivalent single lightning used for simple calculation is equal to the amplitude I ₁ of the first pulse lightning in the process of multiple lightning strikes, that is, both are equal to I _m , the wave head time t _f is 2.6 μs, and the wave tail time t _R is determined by the total charge, and the relationship between t _R and Q _eq can be approximately equivalent to the following formula:

In the above formula, T represents the lightning action time, usually the maximum value is 0.2s;

Through the above-mentioned equivalent adjustment method of amplitude and waveform, the multiple lightning strikes in nature (not limited to the triple lightning situation of Q1, Q2, and Q3 above) are equivalent to a single pulse lightning strike, and then the calculation of the lightning arrester's absorption at both ends of the arrester is quicker and easier. Energy E, by comparing E≥E ₀ , it is judged whether there is a lightning tripping accident in theory, so as to obtain the lightning withstand level E _L0 of the transmission line.

It is worth mentioning that the present invention takes into account the complex wiring of super-long transmission lines, so the lightning tripping rate of the entire transmission line is obtained by calculating the lightning tripping rate q per 100km in sections, which is also for improving the calculation of parameters Accuracy rate, and the lightning tripping rate q per 100km obtained in the above step 4 can also be applied to the calculation of the lightning tripping rate of longer or shorter transmission lines that cancel the lightning protection line according to the actual situation (such as the situation of 10-50km), In addition, the method of the present invention is particularly suitable to be realized by computer software, so the method for calculating the lightning protection performance of a transmission line without lightning protection line can be realized by using a non-transitory computer-readable storage medium with computer instructions or a computer including a processor.

The beneficial effects of the invention are: the method is used in the calculation of lightning protection performance parameter setting of the transmission line, and the influence of long distance and multiple lightning on the lightning resistance level of the transmission line is considered. Compared with the traditional lightning protection performance setting calculation method, the present invention can more accurately evaluate the lightning protection performance of the transmission line under the condition of canceling the lightning protection line, and the parameters are relatively accurate and the calculation amount is small, thereby facilitating the lightning protection of the transmission line Guide the configuration and installation of equipment.

Finally, it is 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 still can The technical solutions described in the foregoing embodiments are modified, or some of the technical features are replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (7)

1. A method for calculating lightning protection performance of a power transmission line without a lightning conductor is characterized by comprising the following steps of 1-4:

step 1: calculating to obtain the lightning activity characteristics of the whole line according to a regulation method and a statistical method, wherein the parameters of the lightning activity characteristics comprise line lightning falling density N (I) and lightning current amplitude probability distribution P (I), and calculating to obtain the line lightning falling frequency sigma of each 100km of power transmission lines according to the line lightning falling density N (I);

step 2: establishing an electromagnetic transient simulation model, calculating to obtain distribution characteristics of lightning current and overvoltage of the power transmission line under different lightning stroke conditions, and obtaining energy E absorbed by the lightning arrester by combining with the probability distribution P (I) of the lightning current amplitude related to the lightning current;

the method for calculating the energy E absorbed by the lightning arrester adopts the following equivalent calculation method of multiple mines and single mine: the amplitude and the wave head time of the equivalent single lightning wave are equal to the amplitude and the wave head time of the first lightning pulse current in the multiple lightning currents, and the total charge of the equivalent single lightning wave is equal to the total charge of the multiple lightning, so that the wave tail time of the equivalent single lightning is determined; the equivalent calculation method of the multiple mines and the single mine further comprises the following steps:

time t of wave tail _R Total charge Q of equivalent single lightning current _eq The following equation can be approximated:

in the above formula, T represents lightning action time, I _eq The amplitude of the equivalent singlet thunder is obtained;

and step 3: calculating to obtain the energy absorption capacity E of the arrester according to the insulator design parameters of the arrester ₀ Judging whether the energy E absorbed by the lightning arrester is more than or equal to the energy absorption capacity E of the lightning arrester under different lightning stroke conditions ₀ So as to obtain lightning-resistant level E of the power transmission line _L0 The lightning resistance level of the power transmission line E _L0 Absorbing energy E to E for lightning arrester ₀ The corresponding lightning current energy value;

and 4, step 4: according to the lightning energy E _L Lightning current amplitude probability distribution P (I), line lightning falling frequency sigma and lightning resistance level E of power transmission line _L0 Calculating the lightning trip-out rate q of the power transmission line with the length of 100km, wherein the calculation mode of q is as follows:

q＝P(E _L )×σ

wherein the lightning current energy E _L Related to the probability distribution P (I), P (E) of the lightning current amplitude _L ) Representing the energy E of lightning current _L Beyond lightning endurance level E _L0 The probability of (d); and after the lightning trip-out rate q is obtained, calculating the lightning trip-out rate of the whole line according to the lightning trip-out rate q of every 100 km.

2. The lightning protection performance calculation method according to claim 1, wherein the step 1 further comprises:

the calculation formula of the lightning current amplitude probability distribution P (I) is as follows:

wherein a represents the average value of the lightning current amplitude of the line, b represents the probability distribution index, the values of a and b are determined by the wave head time and the wave tail time of the lightning current, and the independent variable I represents the lightning current amplitude.

3. The lightning protection performance calculation method according to claim 1, wherein the step 1 of calculating the number σ of lightning strikes of the line per 100km of the power transmission line according to the line lightning strike density N (I) specifically includes:

calculating the number of lightning falling times of the line through the lightning falling density of the power transmission corridor and the lightning guiding width Y of every 1km, wherein the formula of the lightning guiding width Y is as follows:

Y＝4h+b

wherein Y represents the lightning strike width, h represents the average width of the wires, and b represents the outermost wire distance;

the formula of the number σ of lightning falling of the line is as follows:

σ＝N(I)*100*Y

the number σ of lightning falls on the line is a floating point number with a decimal number.

4. The lightning protection performance calculation method according to claim 1, wherein the energy E absorbed by the lightning arrester in the step 2 is calculated by:

the overvoltage at two ends of the lightning arrester and the lightning current waveform flowing through the lightning arrester are obtained through the simulation calculation of the electromagnetic transient simulation model, and the energy E absorbed by the lightning arrester is determined by the following formula:

and when the E exceeds the energy absorption capacity E0 of the lightning arrester, the power transmission line is considered to have a trip accident, wherein u (T) and I (T) respectively represent lightning overvoltage and lightning current at two ends of the lightning arrester, T represents time, T represents lightning action time, E represents energy absorbed by the lightning arrester, and the lightning current I (T) at two ends of the lightning arrester is related to lightning current amplitude probability distribution P (I).

5. The lightning protection performance calculation method according to claim 1, wherein the step 4 further comprises: said lightning energy E _L The calculation formula of (2) is specifically:

wherein P (I) represents a lightning over-current distribution function closely related to the lightning current amplitude probability distribution P (I), u _L And (T) represents the overvoltage generated by lightning current on the power transmission line, and T represents the lightning action time.

6. The utility model provides a cancel lightning conductor transmission line lightning protection performance computing device which characterized in that includes:

at least one processor; and

at least one memory communicatively coupled to the processor, wherein:

the memory stores program instructions executable by the processor, the processor invoking the program instructions to perform the lightning protection performance calculation method of any one of claims 1 to 5.

7. A non-transitory computer-readable storage medium storing computer instructions for causing a computer to perform the lightning protection performance calculation method according to any one of claims 1 to 5.

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