CN102882176A - Method for selecting erection height of lightning conductor of 10kV overhead distribution line - Google Patents

Abstract

The invention discloses a method for selecting the erection height of a lightning conductor of a 10kV overhead distribution line. The method comprises the following steps: (1) building and obtaining a mathematical model of the height of the lightning conductor; (2) obtaining a maximum of a lightning conductor height function; (3) calculating a phase conductor stress and a lightning conductor stress under a current meteorological condition; (4) calculating height maximum Hm of the lightning conductor under a different-span length 1; (5) calculating the coupling performance of the lightning conductor and the phase conductor at different heights of the lightning conductor; and (6) selecting the suitable height of the lightning conductor. According to the invention, the erection height of the lightning conductor can be analyzed and selected in the terms of mechanical stress and electrical coupling performance in a scientific and reasonable manner. The method provided by the invention is simple and feasible, and has good engineering use significance.

Description

A kind of 10kV distribution overhead line lightning conducter antenna height method for selecting

Technical field

The present invention relates to the distribution network line design field, particularly a kind of 10kV distribution overhead line lightning conducter antenna height method for selecting.

Background technology

Power distribution network is the network that directly distributes electric energy to vast power consumer, thereby the safety of power distribution network and power supply reliability more and more come into one's own.The 10kV overhead distribution is the important component part of power distribution network, low, the complex distribution of himself insulation level, and the tripping operation failure rate is high.In distribution line trip accident reason, the accident that thunderbolt causes accounts for the 70%-80% of total accident.The lightning protection of distribution line is the important component part in the work of current mains supply stability.

The distribution line safeguard procedures mainly contain reinforced insulation, reduce pole tower ground resistance, set up lightning conducter, set up zinc oxide arrester, set up discharge insulator, set up overvoltage protection device etc. both at home and abroad at present.Current, the 10kV power distribution network uses the distribution lightning arrester in a large number, in order to avoid controller switching equipment is damaged under lightning overvoltage.Be in operation, because of lightning arrester quality problems and operation maintenance some lightning arrester generation breakdown faults that make not in place.After the puncture, the 10kV link tester is crossed lightning arrester ground connection is occured, and must have a power failure and could process isolated fault, so reduced to a certain extent power supply reliability.

Because lightning conducter is preventing that thunder and lightning from attacking directly and the lifting line lightning resisting level has remarkable result, its lightning protection measures at transmission line is widely used.110kV and above grade transmission line be along completely setting up lightning conducter, and power distribution network is because the shortcoming such as circuit complex distribution, shaft tower size be little, and it is comparatively rare in the 10kV distribution to set up lightning conducter.Because lightning conducter can obviously reduce induction overvoltage on the wire to the coupling of wire and shielding action, concentrate at part damage to crops caused by thunder, important leap, lightning conducter is set up in densely populated areas that practical feasibility is arranged.

The protective mechanism of lightning conducter is as follows:

(1) direct lightning strike protection

In the 10kv power distribution network, newly-built or transformation line sectionalizing are set up lightning conducter needs under the prerequisite that is normally satisfying mechanical stress and electrical distance requirement on the working line extend upward one section tower head at cat head, connect by gold utensil and support.

The distance that suitably increases between lightning conducter and the wire cross-arm can make upper conductor go out the increase of earth-wire protection width and covering upper conductor.In addition, when thunder and lightning hits in overhead line structures, have coupling between ground wire and the wire, they can reduce the insulator string both end voltage, and line lightning resisting level is improved.

When the thunderbolt electric power pylon, lightning conducter is shunted a part of lightning current, because lightning conducter links to each other with shaft tower, its voltage equals shaft tower tie point place voltage, thereby this part voltage has reduced the insulator string both end voltage by being superimposed upon with the effect of wire coupling on the wire, and line lightning resisting level is improved.

(2) induction thunder protection

When 10kV overhead distribution during without lightning conducter, the superpotential computing formula of line influence is:

U _D=-ah _Dt/τ _f

Wherein, U _DBe the induction overvoltage on the wire, h _DFor the wire equivalence to ground level, a is lightning current steepness, t is the time, τ _fBe the time before the lightning current wave.

When construction of line lightning conducter, can produce equally an induced voltage Ug on the lightning conducter, arrester ground, in order to keep 0 current potential of lightning conducter, can a long-living value on the lightning conducter be-voltage of Ug, under the effect of-Ug, every wire component of voltage that all can be coupled, its value is-kUg that k is the coupling coefficient of lightning conducter and phase conductor.The voltage of lightning conducter and phase conductor voltage difference are little, can think Ug=U.Therefore, have the simplification computing formula of phase conductor induction overvoltage under the lightning conducter shielding action to be:

U′ _D=-ah _D(1-kh _B/h _D)t/τ _f

Wherein, h _BFor the lightning conducter equivalence to ground level;

Because the wire coupling coefficient close to the lightning conducter is large, by following formula as can be known, the induction thunder is done the time spent, and the coupling of upper, middle and lower wire is strengthened successively.

Summary of the invention

The above-mentioned shortcoming that the object of the invention is to overcome prior art provides a kind of 10kV distribution overhead line lightning conducter antenna height method for selecting with not enough, improves economy and the fail safe of distribution line lightning protection properties.

Purpose of the present invention is achieved through the following technical solutions:

A kind of 10kV distribution overhead line lightning conducter antenna height method for selecting may further comprise the steps:

(1) make up the Mathematical Modeling of asking for the lightning conducter height:

(i) satisfy following relation apart from S and span length l between span centre drift and lightning conducter:

S≥1+0.012l （1）

(ii) relation apart from S and lightning conducter height H between span centre drift and lightning conducter satisfies following formula:

S=H+f _D-f _B （2）

Wherein, $f_D=\frac{{\mathrm{<figure-callout\; id="2"\; label="g\; D\; l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">g</figure-callout>}}_D{l}^{}{}^2}{8{\mathrm{\&sigma;}}_D};$ $f_B=\frac{{\mathrm{<figure-callout\; id="2"\; label="g\; B\; l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">g</figure-callout>}}_B{l}^{}{}^2}{{8\mathrm{\&sigma;}}_B};$

f _DSag for the span centre drift; f _BSag for lightning conducter; g _DBe span centre drift carrying from anharmonic ratio under current meteorological condition; g _BBe lightning conducter carrying from anharmonic ratio under current meteorological condition; σ _DBe the minimum point stress of span centre drift under current meteorological condition; σ _BBe the minimum point stress of lightning conducter under current meteorological part;

(2) ask for lightning conducter height function maximum:

Got by formula (1) formula (2)

$S=H+(\frac{g_D}{{8\mathrm{\&sigma;}}_D}-\frac{g_B}{{8\mathrm{\&sigma;}}_B}){\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">l</figure-callout>}}^2=1+0.012l---\left(3\right)$

Order

$K=\frac{g_D}{{8\mathrm{\&sigma;}}_D}-\frac{g_B}{{8\mathrm{\&sigma;}}_B}---\left(4\right)$

Then

H=1+0.012l-Kl ² (5）

Obtained the maximum H of H by (4) _m

H _m=(36×10 ^-6)/K+1 （6）

(3) σ under the current meteorological condition of calculating _DAnd σ _B:

Calculate σ according to following formula _D

${\mathrm{\&sigma;}}_n-\frac{E_D{g}_n^2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">l</figure-callout>}}^2}{24{\mathrm{\&sigma;}}_n}={\mathrm{\&sigma;}}_D-\frac{E_D{g}_D^2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">l</figure-callout>}}^2}{24{\mathrm{\&sigma;}}_D}-\mathrm{\&alpha;E}(t-t_0)---\left(7\right)$

Wherein, σ _nBe the minimum point stress of span centre drift under known meteorological condition; E _DCoefficient of elasticity for the span centre drift; g _nBe span centre drift carrying from anharmonic ratio under known meteorological condition; g _DBe span centre drift carrying from anharmonic ratio under current meteorological condition; t ₀Be the temperature under the known meteorological condition; T is the temperature under the current meteorological condition;

Calculate σ according to following formula _B:

${\mathrm{\&sigma;}}_m-\frac{E_B{g}_m^2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">l</figure-callout>}}^2}{24{\mathrm{\&sigma;}}_m}={\mathrm{\&sigma;}}_B-\frac{E_B{g}_B^2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">l</figure-callout>}}^2}{24{\mathrm{\&sigma;}}_B}-\mathrm{\&alpha;E}(t-t_0)---\left(8\right)$

Wherein, σ _mBe the minimum point stress of lightning conducter under known meteorological condition; E _BCoefficient of elasticity for lightning conducter; g _mBe lightning conducter carrying from anharmonic ratio under known meteorological condition; g _BBe lightning conducter carrying from anharmonic ratio under current meteorological condition;

(4) σ that step (3) is obtained _DAnd σ _BSubstitution (4) and formula (6), and calculate lightning conducter height maximum H under the different span length l _m

(5) coupling performance of lightning conducter and phase conductor under the different lightning conducter height of calculating:

Calculate the coupling coefficient of lightning conducter and phase conductor under the different lightning conducter height:

$k=\frac{Z_{\mathrm{BD}}}{Z_{\mathrm{BB}}+{2R}_G}$

Wherein, Z _BDMutual wave impedance for lightning conducter and phase conductor; Z _BBFor lightning conducter from wave impedance; R _GEarth resistance for lightning conducter;

(6) according to the result of step (4) and step (5) gained, selected suitable lightning conducter height.

The coupling performance of lightning conducter and phase conductor under the different lightning conducter height of the described calculating of step (5) also comprises and calculates under the different lightning conducter height induction overvoltage U ' on the phase conductor _D, specifically calculate according to following formula:

${U^{\&prime;}}_D=U_D(1-k\frac{h_B}{h_D})$

Wherein, U _DFor without lightning conducter the time, the induction overvoltage on the phase conductor; h _DFor the phase conductor equivalence to ground level; h _BFor the lightning conducter equivalence to ground level.

Compared with prior art, the present invention has the following advantages and beneficial effect: the present invention has overcome when setting 10kV distribution overhead line sets up the lightning conducter height on the present engineering, the operations staff can only transform shaft tower with reference to operating experience, by setting up Mathematical Modeling, analyze the selected suitable lightning conducter height of data, realized scientific and reasonable from mechanical stress and the selected lightning conducter antenna height of electrical couplings performance perspective analysis, thereby make Electric Design department or operation power attendant that the normative reference that quantizes arranged in track remodelling and new line planning process, also for the lightning protection measures assessment of power department in lightening protection engineering reference frame is arranged, and set up lightning conducter at power distribution network, improve the lightning withstand level of the circuit of knowing clearly, reduced the size of induction overvoltage, by the waste of material that sets up lightning conducter at power distribution network has been saved in the calculating of support height, for power distribution network has brought huge economic benefit; Simultaneously, implementation method of the present invention is easy, has good engineering and uses meaning.

Description of drawings

Fig. 1 is wire and lightning conducter sag schematic diagram.

Fig. 2 is H _mChange curve under different spans.

Fig. 3 thunder and lightning induction voltage reduction amount during the different support height when adopting the vertical rounded projections arranged of single loop wire.

Fig. 4 thunder and lightning induction voltage reduction amount during the different support height when adopting single loop wire transverse triangle shape to arrange.

Embodiment

Below in conjunction with embodiment and accompanying drawing, the present invention is described in further detail, but embodiments of the present invention are not limited to this.

Embodiment

A kind of 10kV distribution overhead line lightning conducter antenna height method for selecting may further comprise the steps:

(1) make up the Mathematical Modeling of asking for the lightning conducter height:

(i) satisfy following relation apart from S and span length l between span centre drift and lightning conducter:

S≥1+0.012l （1）

(ii) as shown in Figure 1, satisfy following formula apart from S and lightning conducter height relationships between span centre drift and lightning conducter:

S＝H+f _D-f _B （2）

Wherein, $f_D=\frac{{\mathrm{<figure-callout\; id="2"\; label="g\; D\; l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">g</figure-callout>}}_D{l}^{}{}^2}{8{\mathrm{\&sigma;}}_D};$ $f_B=\frac{{\mathrm{<figure-callout\; id="2"\; label="g\; B\; l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">g</figure-callout>}}_B{l}^{}{}^2}{{8\mathrm{\&sigma;}}_B};$

f _DSag for the span centre drift; f _BSag for lightning conducter; g _DBe carrying from anharmonic ratio of span centre drift; g _BBe carrying from anharmonic ratio of lightning conducter; σ _DBe the minimum point stress of span centre drift under current meteorological condition; σ _BBe the minimum point stress of lightning conducter under current meteorological part;

(2) ask for lightning conducter height function maximum:

Got by formula (1) formula (2)

$S=H+(\frac{g_D}{{8\mathrm{\&sigma;}}_D}-\frac{g_B}{{8\mathrm{\&sigma;}}_B}){\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">l</figure-callout>}}^2=1+0.012l---\left(3\right)$

Order

$K=\frac{g_D}{{8\mathrm{\&sigma;}}_D}-\frac{g_B}{{8\mathrm{\&sigma;}}_B}---\left(4\right)$

In Practical Project, the K value is greater than zero, then

H=1+0.012l-Kl ² （5）

To formula (4) differentiate: $\frac{\mathrm{dH}}{\mathrm{dl}}=0.012-2\mathrm{Kl}=0$

That is: $l=\frac{0.006}{K}$

According to

$\frac{\mathrm{dH}}{\mathrm{dl}}=0;$ $\frac{d^2\mathrm{<figure-callout\; id="2"\; label="H\; d\; l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">H</figure-callout>}}{d{l}^{}}=-2K<0$

Obtain the maximum H of H _m

H _m＝(36×10 ^-6)/K+1 （6）

(3) σ under the current meteorological condition of calculating _DAnd σ _B:

Calculate σ according to following formula _D

${\mathrm{\&sigma;}}_n-\frac{E_D{g}_n^2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">l</figure-callout>}}^2}{24{\mathrm{\&sigma;}}_n}={\mathrm{\&sigma;}}_D-\frac{E_D{g}_D^2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">l</figure-callout>}}^2}{24{\mathrm{\&sigma;}}_D}-\mathrm{\&alpha;E}(t-t_0)---\left(7\right)$

Wherein, σ _nBe the minimum point stress of span centre drift under known meteorological condition; E _DCoefficient of elasticity for the span centre drift; g _nBe span centre drift carrying from anharmonic ratio under known meteorological condition; g _DBe span centre drift carrying from anharmonic ratio under current meteorological condition; t ₀Be the temperature under the known meteorological condition; T is the temperature under the current meteorological condition;

Calculate σ according to following formula _B:

${\mathrm{\&sigma;}}_m-\frac{E_B{g}_m^2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">l</figure-callout>}}^2}{24{\mathrm{\&sigma;}}_m}={\mathrm{\&sigma;}}_B-\frac{E_B{g}_B^2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001911541100022.png"\; state="\{\{state\}\}">l</figure-callout>}}^2}{24{\mathrm{\&sigma;}}_B}-\mathrm{\&alpha;E}(t-t_0)---\left(8\right)$

Wherein, σ _mBe the minimum point stress of lightning conducter under known meteorological condition; E _BCoefficient of elasticity for lightning conducter; g _mBe lightning conducter carrying from anharmonic ratio under known meteorological condition; g _BBe lightning conducter carrying from anharmonic ratio under current meteorological condition;

(4) σ that step (3) is obtained _DAnd σ _BSubstitution (4) and formula (6), and calculate lightning conducter height maximum H under the different span length l _m

It is LGJ-240/40 that present embodiment is selected the model of phase conductor, and Calculation Section amasss A=277.75mm ², calculate pull-off force T _p=83370N, thermalexpansioncoefficientα=18.9 * 10 ^-6/ ℃, coefficient of elasticity E=76000MPa, the model of lightning conducter is GJ-50, Calculation Section amasss A=49.50mm ², calculate pull-off force T _p=53500N, thermalexpansioncoefficientα=11.5 * 10 ^-6/ ℃, coefficient of elasticity E=181400MPa.

H when calculating different ruling span _mValue (seeing Table 1) and H _mCurve chart (Fig. 2) with the span variation.

The value of table 1 lightning conducter height maximum under different spans

(5) coupling performance of lightning conducter and phase conductor under the different lightning conducter height of calculating:

Calculate the coupling coefficient of lightning conducter and phase conductor under the different lightning conducter height:

$k=\frac{Z_{\mathrm{BD}}}{Z_{\mathrm{BB}}+{2R}_G}$

Wherein, Z _BDMutual wave impedance for lightning conducter and phase conductor; Z _BBFor lightning conducter from wave impedance; R _GEarth resistance for lightning conducter;

Calculate the induction overvoltage U ' on the phase conductor under the different lightning conducter height _D, concrete according to formula calculating once:

${U^{\&prime;}}_D=U_D(1-k\frac{h_B}{h_D})$

Wherein, U _DFor without lightning conducter the time, the induction overvoltage on the phase conductor; h _DFor the phase conductor equivalence to ground level; h _BFor the lightning conducter equivalence to ground level.

For the vertical rounded projections arranged of single loop wire commonly used, the coupling coefficient of lightning conducter and phase conductor sees Table 2 under the different lightning conducter height that present embodiment obtains, actual sensed overvoltage U ' on the phase conductor under the different lightning conducter height _DSee Fig. 3.

The coupling coefficient of lightning conducter and each phase under the different lightning conducter support heights of table 2

Arrange for single loop wire transverse triangle shape commonly used, the coupling coefficient of lightning conducter and phase conductor sees Table 3 under the different lightning conducter height that present embodiment obtains, induction overvoltage U ' on the phase conductor under the different lightning conducter height _DSee Fig. 4.

The coupling coefficient of lightning conducter and each phase under the different lightning conducter support heights of table 3

(6) according to the result of step (4) and step (5) gained, namely table 1, table 2, Fig. 3, Fig. 4 select suitable lightning conducter height.

Above-described embodiment is the better execution mode of the present invention; but embodiments of the present invention are not limited by the examples; other any do not deviate from change, the modification done under Spirit Essence of the present invention and the principle, substitutes, combination, simplify; all should be the substitute mode of equivalence, be included within protection scope of the present invention.

Claims (2)

1. a 10kV distribution overhead line lightning conducter antenna height method for selecting is characterized in that, may further comprise the steps:

(1) make up the Mathematical Modeling of asking for the lightning conducter height:

(i) satisfy following relation apart from S and span length l between span centre drift and lightning conducter:

S≥1+0.012l （1）

(ii) relation apart from S and lightning conducter height H between span centre drift and lightning conducter satisfies following formula:

S=H+f _D-f _B （2）

Wherein, $f_D=\frac{g_D{l}^2}{8{\mathrm{\&sigma;}}_D};$ $f_B=\frac{g_B{l}^2}{8{\mathrm{\&sigma;}}_B};$

f _DSag for the span centre drift; f _BSag for lightning conducter; g _DBe span centre drift carrying from anharmonic ratio under current meteorological condition; g _BBe lightning conducter carrying from anharmonic ratio under current meteorological condition; σ _DBe the minimum point stress of span centre drift under current meteorological condition; σ _BBe the minimum point stress of lightning conducter under current meteorological part;

(2) ask for lightning conducter height function maximum:

Got by formula (1) formula (2)

$S=H+(\frac{g_D}{8{\mathrm{\&sigma;}}_D}-\frac{g_B}{8{\mathrm{\&sigma;}}_B})l^2=1+0.012l---\left(3\right)$

Order

$K=\frac{g_D}{8{\mathrm{\&sigma;}}_D}-\frac{g_B}{8{\mathrm{\&sigma;}}_B}---\left(4\right)$

Then

H=1+0.012l-Kl ² (5）

Tried to achieve the maximum H of H by formula (4) _m

H _m=(36×10 ^-6)/K+1 （6）

(3) σ under the current meteorological condition of calculating _DAnd σ _B:

Calculate σ according to following formula _D

${\mathrm{\&sigma;}}_n-\frac{E_D{g}_n^2{l}^2}{24{\mathrm{\&sigma;}}_n}={\mathrm{\&sigma;}}_D-\frac{E_D{g}_D^2{l}^2}{24{\mathrm{\&sigma;}}_D}-\mathrm{\&alpha;E}(t-t_0)---\left(7\right)$

Wherein, σ _nBe the minimum point stress of span centre drift under known meteorological condition; E _DCoefficient of elasticity for the span centre drift; g _nBe span centre drift carrying from anharmonic ratio under known meteorological condition; g _DBe span centre drift carrying from anharmonic ratio under current meteorological condition; t ₀Be the temperature under the known meteorological condition; T is the temperature under the current meteorological condition;

Calculate σ according to following formula _B:

${\mathrm{\&sigma;}}_m-\frac{E_B{g}_m^2{l}^2}{24{\mathrm{\&sigma;}}_m}={\mathrm{\&sigma;}}_B-\frac{E_B{g}_B^2{l}^2}{24{\mathrm{\&sigma;}}_B}-\mathrm{\&alpha;E}(t-t_0)---\left(8\right)$

Wherein, σ _mBe the minimum point stress of lightning conducter under known meteorological condition; E _BCoefficient of elasticity for lightning conducter; g _mBe lightning conducter carrying from anharmonic ratio under known meteorological condition; g _BBe lightning conducter carrying from anharmonic ratio under current meteorological condition;

(4) σ that step (3) is obtained _DAnd σ _BSubstitution (4) and formula (6), and calculate lightning conducter height maximum H under the different span length l _m

(5) coupling performance of lightning conducter and phase conductor under the different lightning conducter height of calculating:

Calculate the coupling coefficient of lightning conducter and phase conductor under the different lightning conducter height:

$k=\frac{Z_{\mathrm{BD}}}{Z_{\mathrm{BB}}+2R_G}$

Wherein, Z _BDMutual wave impedance for lightning conducter and phase conductor; Z _BBFor lightning conducter from wave impedance; R _GEarth resistance for lightning conducter;

(6) according to the result of step (4) and step (5) gained, selected suitable lightning conducter height.

2. 10kV distribution overhead line lightning conducter antenna height method for selecting according to claim 1, it is characterized in that, the coupling performance of lightning conducter and phase conductor under the different lightning conducter height of the described calculating of step (5) also comprises and calculates under the different lightning conducter height induction overvoltage U ' on the phase conductor _D, specifically calculate according to following formula:

${U^{\&prime;}}_D=U_D(1-k\frac{h_B}{h_D})$

Wherein, U _DFor without lightning conducter the time, the induction overvoltage on the phase conductor; h _DFor the phase conductor equivalence to ground level; h _BFor the lightning conducter equivalence to ground level.

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