CN102662119B - 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.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, wherein more than approximately 80% cause for responding to thunder, and approximately 20% causes for direct lightning strike.In the distribution line of various electric pressures, because dielectric level is lower, especially easily there is lightning stroke trip accident in low pressure (as 6kV, 10kV) distribution line.Visible, low-voltage distributing line is responded to thunder and the trip accident that causes occupies very large 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 lightning protection measures low-voltage distributing line responded to the risk tripping after thunder have much, but not yet have perfect method to assess this risk 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 assess low-voltage distributing line the risk tripping after thunder, 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 to low-voltage distributing line: the amplitude of lightning current critical value I that produces lightning induced voltage on circuit ₀, circuit average height h, insulator chain impulse flashover voltage U _50%, amplitude of lightning current I;

Calculate according to the following formula 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 formula, p (I) represents amplitude of lightning current probability density function, S _m(I), while producing lightning induced voltage on 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, comprising:

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

Tripping frequency determination module, for calculating according to the following formula 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 formula, p (I) represents amplitude of lightning current probability density function, S _m(I), while producing lightning induced voltage on 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, first gather correlation parameter, again by the specific formula of parameter substitution gathering, gained is responded to thunder tripping frequency as the evaluation criteria of weighing induction thunder tripping operation risk, for formulation and the comparation and assessment etc. of low-voltage distributing line lightning protection measures 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 gained tripping frequency has reflected 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 combined with apparatus for evaluating, can realize the object of risk assessment.

Brief description of the drawings

Fig. 1 is induction thunder thunderbolt the earth schematic 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 common-tower double-return low-voltage distributing line schematic diagram;

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

Embodiment

The present invention reflects tripping operation risk by tripping frequency, for formulation and the assessment of low-voltage distributing line lightning protection measures provide reliable foundation.Below taking 10kV distribution line as example, and explain in detail the present invention with embodiment by reference to the accompanying drawings.

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

The lightning induced voltage schematic diagram that Fig. 1 produces while being near the earth of thunderbolt 10kV distribution line, wherein the horizontal range of lightning strike spot position and 10kV distribution line is S, now A, B, C three-phase will produce lightning induced voltage simultaneously.The lightning induced voltage producing when A, B two-phase is greater than insulator chain surge voltage tolerance value U _50%time, A, B two-phase by the while over the ground flashover cause phase fault to make line tripping; When A, B, C three-phase induction lightning overvoltage are greater than insulator chain surge voltage tolerance value U _50%time, three-phase is while flashover over the ground almost, causes three-phase shortcircuit to make circuit breaker trip.

The lightning induced voltage size that China's code produces while specifying thunderbolt the earth on wire is:

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

U _grepresent lightning induced voltage, I represents amplitude of lightning current, and h represents the average height of circuit, and S represents the horizontal range of lightning strike spot to circuit.A lot of research shows: lightning strike spot apart from circuit 65m with interior shaft tower and the circuit generally can attacked directly.To this, think that 65m is the bee-line of 10kV distribution line generation lightning induced voltage herein, i.e. S >=65.

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

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

In the time that amplitude of lightning current is I, cause circuit to produce the ultimate range S of lightning induced voltage _m(I) meet:

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

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 formula, p (I) is amplitude of lightning current probability density function, and China's code 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 as follows:

Step S1, the data that collection is relevant to low-voltage distributing line: the amplitude of lightning current critical value I that produces lightning induced voltage on 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 relating to and cause circuit to produce the ultimate range S of lightning induced voltage _m(I), adopt corresponding formula to calculate.

For common-tower double-return 10kV distribution line as shown in Figure 3, the frequency that generation double back trips because of lightning induced voltage is simultaneously:

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

In formula, l is the distance between the horizontal wire of two-phase.

In the time that this appraisal procedure is applied to circuit shown in Fig. 3, step S1 is image data l also, and calculates common-tower double-return 10kV distribution line according to formula (5) and respond to the frequency that thunder trips simultaneously.For example 10kV distribution shaft tower upper, middle and lower three-phase conducting wire hanging point height is as shown in Figure 3 respectively 13m, 12m, 11m, and cross-arm length is 1m, adopts porcelain-arm insulator, insulator chain flashover voltage U _50%=250kV, dry arcing distance is 0.38m.Above-mentioned parameter substitution formula (4), (5) are obtained to 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, as shown in Figure 4, comprising:

Data acquisition module, for gathering the data relevant with low-voltage distributing line: the amplitude of lightning current critical value I that produces lightning induced voltage on 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;

Tripping frequency determination module, for calculating low-voltage distributing line induction thunder tripping frequency N according to formula (4) _sFFOR.

From describing above and Fig. 4, data acquisition module is connected and has formed this apparatus for evaluating with tripping frequency determination module.

As a preferred embodiment, described acquisition module is also for gathering the horizontal range l between common-tower double-return low-voltage distributing line, and described tripping frequency determination module is also responded to the frequency N of thunder tripping operation simultaneously for calculating common-tower double-return low-voltage distributing line according to formula (5) _sFFOR2.

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

Appraisal procedure of the present invention is combined with apparatus for evaluating, can realizes the object of tripping operation risk assessment.

The above embodiment has only expressed several embodiment of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, 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 claims.

Claims (4)

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

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

Calculate according to the following formula 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 formula, p (I) represents amplitude of lightning current probability density function, S _m(I), while representing to produce lightning induced voltage on low-voltage distributing line, lightning strike spot is apart from the ultimate range of low-voltage distributing line,

In the time that this method is applied to common-tower double-return low-voltage distributing line, the data of collection also comprise the horizontal range l between common-tower double-return low-voltage distributing line, calculate according to the following formula common-tower double-return low-voltage distributing line and respond to the frequency N that thunder trips simultaneously _sFFOR2:

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

I ₁represent on double-circuit line, to produce in common-tower double-return low-voltage distributing line the critical value of the amplitude of lightning current of lightning induced voltage simultaneously.

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

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

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

Tripping frequency determination module, for calculating according to the following formula 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 formula, p (I) represents amplitude of lightning current probability density function, S _m(I), while representing to produce lightning induced voltage on low-voltage distributing line, lightning strike spot is apart from the ultimate range of low-voltage distributing line,

Described acquisition module is also for gathering the horizontal range l between common-tower double-return low-voltage distributing line, and described tripping frequency determination module is also responded to the frequency N of thunder tripping operation simultaneously for calculating according to the following formula common-tower double-return low-voltage distributing line _sFFOR2:

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

I ₁represent on double-circuit line, to produce in common-tower double-return low-voltage distributing line the critical value of the amplitude of lightning current of lightning induced voltage simultaneously.

4. low-voltage distributing line induction thunder tripping operation risk assessment device according to claim 3, is characterized in that, the expression formula of described p (I) is described S _m(I) expression formula is