CN102662119A - Method and device for evaluating risks of tripping of low-voltage distribution line in lightning induction - Google Patents

Abstract

The invention discloses a method for evaluating risks of tripping of a low-voltage distribution line in lightning induction. The method includes the steps: firstly, acquiring relevant parameters; and then, substituting the acquired parameters to a specific formula, and using a lightning induction tripping frequency as an evaluative criteria for measuring the lightning induction tripping risks, so as to provide a reliable basis for formulation, evaluation and the like of lightning protection measures for the low-voltage distribution line. By the aid of the method for evaluating the risks of tripping of the low-voltage distribution line in lightning induction, data required to be acquired are easy to obtain, complicated operation is not involved in the whole process, and the obtained tripping frequency can accurately reflect the tripping risks. The invention further discloses a device for evaluating the risks of tripping of the low-voltage distribution line in lightning induction, and the device corresponds to the method. The risks of tripping in lightning induction can be evaluated by means of combination use of the method with the device.

Description

Low-voltage distributing line induction thunder tripping operation methods of risk assessment and device

Technical field

The present invention relates to distribution line shocking preventing technology field, particularly relate to a kind of low-voltage distributing line induction thunder tripping operation methods of risk assessment and device.

Background technology

According to the difference of lightning strike spot position, the thunderbolt that distribution line suffers can be divided into direct lightning strike and induction thunder.The investigation data show: distribution line damage to crops caused by thunder accident accounts for the 70-80% of whole electric system damage to crops caused by thunder accident, causes for responding to thunder 80% or more wherein approximately, and about 20% causes for direct lightning strike.In the distribution line of various electric pressures, because dielectric level is lower, the lightning stroke trip accident takes place in low pressure (like 6kV, 10kV) distribution line especially easily.It is thus clear that low-voltage distributing line is responded to thunder and the tripping operation accident that causes is occupied very big proportion in whole electric system damage to crops caused by thunder accident, formulates corresponding lightning protection measures and seems particularly important.Formulate need to understand before the lightning protection measures low-voltage distributing line responded to the risk that trips behind the thunder have much, but do not have perfect method to assess this risk as yet at present.

Summary of the invention

Based on above-mentioned situation, the present invention proposes a kind of low-voltage distributing line induction thunder tripping operation methods of risk assessment and device, responded to the risk that trips behind the thunder with the assessment low-voltage distributing line, for the formulation of lightning protection measures provides support.

A kind of low-voltage distributing line induction thunder tripping operation methods of risk assessment comprises step:

Gather the data relevant: the amplitude of lightning current critical value I that produces lightning induced voltage on the circuit with low-voltage distributing line ₀, circuit average height h, insulator chain impulse flashover voltage U _50%, amplitude of lightning current I;

According to computes low-voltage distributing line induction thunder tripping frequency N _SFFOR:

$N_{\mathrm{SFFOR}}={\∫}_{I_0}^{\∞}(S_m\left(I\right)-65)p\left(I\right)\mathrm{dI}$

In the formula, p (I) expression amplitude of lightning current probability density function, S _mWhen (I) producing lightning induced voltage on the expression low-voltage distributing line, lightning strike spot is apart from the ultimate range of low-voltage distributing line.

A kind of low-voltage distributing line induction thunder tripping operation risk assessment device comprises:

Data acquisition module is used to gather the data relevant with low-voltage distributing line: the amplitude of lightning current critical value I that produces lightning induced voltage on the circuit ₀, circuit average height h, insulator chain impulse flashover voltage U _50%, amplitude of lightning current I;

The tripping frequency determination module is used for according to computes low-voltage distributing line induction thunder tripping frequency N _SFFOR:

$N_{\mathrm{SFFOR}}={\∫}_{I_0}^{\∞}(S_m\left(I\right)-65)p\left(I\right)\mathrm{dI}$

In the formula, p (I) expression amplitude of lightning current probability density function, S _mWhen (I) producing lightning induced voltage on the expression low-voltage distributing line, lightning strike spot is apart from the ultimate range of low-voltage distributing line.

Low-voltage distributing line induction thunder tripping operation methods of risk assessment of the present invention; Gather correlation parameter earlier; Again with the specific formula of gathering of parameter substitution; Gained is responded to the thunder tripping frequency as the evaluation criteria of weighing induction thunder tripping operation risk, for the formulation of low-voltage distributing line lightning protection measures and comparation and assessment etc. provide reliable foundation.The data of the required collection of this appraisal procedure are easy to obtain, and whole process does not relate to complex calculations, and the gained tripping frequency has reflected the tripping operation risk exactly.Low-voltage distributing line induction thunder tripping operation risk assessment device of the present invention is the device corresponding with above-mentioned appraisal procedure, and appraisal procedure is used in combination with apparatus for evaluating, can realize the purpose of risk assessment.

Description of drawings

Fig. 1 is induction thunder thunderbolt the earth synoptic diagram;

Fig. 2 is low-voltage distributing line induction thunder tripping operation methods of risk assessment schematic flow sheet of the present invention;

Fig. 3 is a common-tower double-return low-voltage distributing line synoptic diagram;

Fig. 4 is low-voltage distributing line induction thunder tripping operation risk assessment apparatus structure synoptic diagram of the present invention.

Embodiment

The present invention reflects the tripping operation risk through tripping frequency, for the formulation and the assessment of low-voltage distributing line lightning protection measures provides reliable foundation.Be example with the 10kV distribution line below, and combine accompanying drawing and the present invention of embodiment illustrated in detail.

Because China≤60kV electric pressure electrical network generally adopts the mode of neutral point indirect earthing, behind the phase insulation flashover, ground current is very little, and arc energy is very fast can not to cause tripping operation from putting out, and circuit can continue distribution.If two phase insulation flashovers take place, then form phase fault, line tripping, thus distribution interrupts.

Near the lightning induced voltage synoptic diagram of Fig. 1 for producing during the earth the thunderbolt 10kV distribution line, wherein the horizontal range of lightning strike spot position and 10kV distribution line is S, A, B, C three-phase will produce lightning induced voltage simultaneously at this moment.The lightning induced voltage that produces mutually as A, B two is greater than insulator chain surge voltage tolerance value U _50%The time, A, B two mutually will be simultaneously over the ground flashover cause phase fault to make line tripping; When A, B, C three-phase induction thunder superpotential greater than insulator chain surge voltage tolerance value U _50%The time, three-phase is flashover over the ground simultaneously almost, causes three-phase shortcircuit to make circuit breaker trip.

The lightning induced voltage size that China's rules regulation produces on lead when being struck by lightning the earth is:

$U_g=\frac{25\mathrm{Ih}}{S}---\left(1\right)$

U _gThe expression lightning induced voltage, I representes amplitude of lightning current, and h representes the average height of circuit, and S representes the horizontal range of lightning strike spot to circuit.A lot of researchs show: lightning strike spot generally can be attacked shaft tower and circuit directly apart from circuit 65m with interior.To this, this paper thinks that 65m is the bee-line of 10kV distribution line generation lightning induced voltage, i.e. S >=65.

Produce the amplitude of lightning current critical value I of lightning induced voltage on the line ₀Satisfy expression formula:

$U_{50\%}=\frac{25I_{0}h}{65}---\left(2\right)$

When amplitude of lightning current is I, cause circuit to produce the ultimate range S of lightning induced voltage _m(I) satisfy:

$S_m\left(I\right)=\frac{25\mathrm{Ih}}{U_{50\%}}---\left(3\right)$

Therefore, 10kV distribution line induction thunder tripping frequency is:

$N_{\mathrm{SFFOR}}={\∫}_{I_0}^{\∞}(S_m\left(I\right)-65)p\left(I\right)\mathrm{dI}---\left(4\right)$

In the formula; P (I) is the amplitude of lightning current probability density function; China's rules regulation amplitude of lightning current probability function is lgP=-I/88, and differential obtains amplitude of lightning current probability density function

Based on formula (3), (4), as shown in Figure 2, the process of low-voltage distributing line induction thunder tripping operation methods of risk assessment of the present invention is following:

Step S1, the data that collection is relevant with low-voltage distributing line: the amplitude of lightning current critical value I that produces lightning induced voltage on the circuit ₀, circuit average height h, line insulator string impulse flashover voltage U _50%, amplitude of lightning current I;

Step S2, calculate low-voltage distributing line induction thunder tripping frequency N according to formula (4) _SFFOR, the amplitude of lightning current probability density function that relates to and cause circuit to produce the ultimate range S of lightning induced voltage _m(I), adopt corresponding formulas to calculate.

For common-tower double-return 10kV distribution line as shown in Figure 3, the frequencies that take place to trip because of lightning induced voltage simultaneously for two times are:

$N_{\mathrm{SFFOR}2}={\∫}_{I_1}^{\∞}(S_m\left(I\right)-l-65)p\left(I\right)\mathrm{dI}---\left(5\right)$

In the formula, l is the distance between the two horizontal mutually leads.

When this appraisal procedure was applied to circuit shown in Figure 3, step S1 is image data l also, and calculated the frequency that common-tower double-return 10kV distribution line is responded to the thunder tripping operation simultaneously according to formula (5).10kV distribution shaft tower upper, middle and lower three-phase conducting wire hanging point height for example as shown in Figure 3 is respectively 13m, 12m, 11m, and cross-arm length is 1m, adopts porcelain-arm insulator, insulator chain flashover voltage U _50%=250kV, dry arcing distance are 0.38m.Above-mentioned parameter substitution formula (4), (5) are got N _SFFOR=11.11; N _SFFOR2=10.65.

Low-voltage distributing line induction thunder tripping operation risk assessment device of the present invention is the device corresponding with above-mentioned appraisal procedure, and is as shown in Figure 4, comprising:

Data acquisition module is used to gather the data relevant with low-voltage distributing line: the amplitude of lightning current critical value I that produces lightning induced voltage on the circuit ₀, circuit average height h, amplitude of lightning current probability density function p (I), low-voltage distributing line insulator chain impulse flashover voltage U _50%And amplitude of lightning current I;

The tripping frequency determination module is used for calculating low-voltage distributing line induction thunder tripping frequency N according to formula (4) _SFFOR

Can know that by above description and Fig. 4 data acquisition module links to each other with the tripping frequency determination module and constituted this apparatus for evaluating.

As a preferred embodiment; Said acquisition module also is used to gather the horizontal range l between the common-tower double-return low-voltage distributing line, and said tripping frequency determination module also is used for calculating the frequency N that the common-tower double-return low-voltage distributing line is responded to the thunder tripping operation simultaneously according to formula (5) _SFFOR2

The other technologies characteristic of this apparatus for evaluating is identical with above-mentioned appraisal procedure, does not repeat them here.

Appraisal procedure of the present invention is used in combination the purpose of the risk assessment that can realize tripping with apparatus for evaluating.

The above embodiment has only expressed several kinds of embodiments of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to claim of the present invention.Should be pointed out that for the person of ordinary skill of the art under the prerequisite that does not break away from the present invention's design, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with accompanying claims.

Claims (6)

1. a low-voltage distributing line induction thunder tripping operation methods of risk assessment is characterized in that, comprises step:

Gather the data relevant: the amplitude of lightning current critical value I that produces lightning induced voltage on the circuit with low-voltage distributing line ₀, circuit average height h, insulator chain impulse flashover voltage U _50%, amplitude of lightning current I;

According to computes low-voltage distributing line induction thunder tripping frequency N _SFFOR:

$N_{\mathrm{SFFOR}}={\∫}_{I_0}^{\∞}(S_m\left(I\right)-65)p\left(I\right)\mathrm{dI}$

In the formula, p (I) expression amplitude of lightning current probability density function, S _mWhen (I) producing lightning induced voltage on the expression low-voltage distributing line, lightning strike spot is apart from the ultimate range of low-voltage distributing line.

2. low-voltage distributing line induction thunder tripping operation methods of risk assessment according to claim 1; It is characterized in that: when this method is applied to the common-tower double-return low-voltage distributing line; The data of gathering also comprise the horizontal range l between the common-tower double-return low-voltage distributing line, respond to the frequency N of thunder tripping operation simultaneously according to computes common-tower double-return low-voltage distributing line _SFFOR2:

$N_{\mathrm{SFFOR}2}={\∫}_{I_1}^{\∞}(S_m\left(I\right)-l-65)p\left(I\right)\mathrm{dI}.$

3. low-voltage distributing line induction thunder tripping operation methods of risk assessment according to claim 1 and 2 is characterized in that the expression formula of said p (I) does Said S _m(I) expression formula does

$S_m\left(I\right)=\frac{25\mathrm{Ih}}{U_{50\%}}.$

4. a low-voltage distributing line induction thunder tripping operation risk assessment device is characterized in that, comprising:

Data acquisition module is used to gather the data relevant with low-voltage distributing line: the amplitude of lightning current critical value I that produces lightning induced voltage on the circuit ₀, circuit average height h, insulator chain impulse flashover voltage U _50%, amplitude of lightning current I;

The tripping frequency determination module is used for according to computes low-voltage distributing line induction thunder tripping frequency N _SFFOR:

$N_{\mathrm{SFFOR}}={\∫}_{I_0}^{\∞}(S_m\left(I\right)-65)p\left(I\right)\mathrm{dI}$

In the formula, p (I) expression amplitude of lightning current probability density function, S _mWhen (I) producing lightning induced voltage on the expression low-voltage distributing line, lightning strike spot is apart from the ultimate range of low-voltage distributing line.

5. low-voltage distributing line induction thunder tripping operation risk assessment device according to claim 3; It is characterized in that; Said acquisition module also is used to gather the horizontal range l between the common-tower double-return low-voltage distributing line, and said tripping frequency determination module also is used for responding to simultaneously according to computes common-tower double-return low-voltage distributing line the frequency N of thunder tripping operation _SFFOR2:

$N_{\mathrm{SFFOR}2}={\∫}_{I_1}^{\∞}(S_m\left(I\right)-l-65)p\left(I\right)\mathrm{dI}.$

6. according to claim 4 or 5 described low-voltage distributing line induction thunder tripping operation risk assessment devices, it is characterized in that the expression formula of said p (I) does

$p\left(I\right)=\frac{\ln 10}{88}{10}^{-\frac{I}{88}},$

Said S _m(I) expression formula does

$S_m\left(I\right)=\frac{25\mathrm{Ih}}{U_{50\%}}.$

Images