CN102818959A - Method for calculating minimum air clear distance of direct current valve hall based on improved clearance coefficient - Google Patents

Abstract

The invention relates to a method for calculating minimum an air clear distance of a direct current valve hall based on an improved clearance coefficient, belonging to the field of designs of direct current transmission lines of transmission and transformation projects. The method comprises the steps of: firstly, obtaining a gap discharge voltage of each gap in a valve hall through a switching impulsive discharge test; then determining a function relationship among the gap discharge voltage, the electrode size and the gap distance by using a least square method; obtaining an improved gap coefficient taking influences of electrode size and gap distance into consideration by using the function relationship; and finally, determining the minimum air clear distance of the direct current valve hall by using an iteration method according to the improved gap coefficient. According to the method provided by the invention, the minimum air clear distance of the direct current valve hall can be obtained by calculation, and can be reduced as far as possible when the operation safety of equipment can be ensured, and project investment is saved.

Description

Based on the straight-wavy valve Room of improving percent break minimum air free distance computation method

Technical field

The present invention relates to a kind of based on the straight-wavy valve Room of improving percent break minimum air free distance computation method; Relate in particular to the method for the air clear distance of electrical equipment in current conversion station in a kind of definite DC transmission system, converting plant, the Inverter Station valve Room, belong to project of transmitting and converting electricity DC power transmission line design field.

Background technology

The straight-wavy valve Room is meant placement converter valve, the rectifying valve of current conversion station in the DC transmission system, converting plant, Inverter Station, the special-purpose place of inversion valve.Between each electrical equipment in the straight-wavy valve Room (like valve, sleeve pipe, transformer) and the air gap distance between equipment and body of wall or the ground, be called the air clear distance.The air clear distance has material impact to construction costs, the factor that must consider when being the design straight-wavy valve Room.The air clear distance is generally determined by the thunder and lightning and the switching impulse sparkover voltage in gap.Right ± the 500kV and the above electric pressure straight-wavy valve Room, the air clear distance that is determined by switching impulse sparkover voltage is generally less than the clearance by the decision of lightning impulse sparking voltage.

At present, the computing method by the minimum air clear distance in the straight-wavy valve Room of switching impulse sparkover voltage decision that extensively adopt in the engineering design are following:

(1) obtains under the standard atmosphere condition superpotential U that the clearance of being considered need tolerate _W-corrU _W-corrComputing formula do

$U_{w-\mathrm{corr}}=\frac{k_m{U}_w}{K_t(1-2\mathrm{\σ})}---\left(1\right)$

U wherein _wSwitching impulse dielectric level for electrical equipment under the typical meteorological condition of the valve Room; k _mIt is design margin; K _tIt is the Atmospheric corrections coefficient; σ is the coefficient of variation of gap discharge voltage, and to switching impulse, σ gets 6%.

(2) calculate minimum air clear distance.Minimum air free distance computation formula does

$L=\sqrt[0.6]{\frac{U_{w-\mathrm{corr}}}{500K}}---\left(2\right)$

Wherein d is minimum air clear distance, and unit is m; K is for characterizing the percent break of electrode shape characteristic, the different different electrode type of coefficient representative, the general selection as follows: line---sheet separation K=1.15, lead---conductor spacing K=1.3, rod---excellent gap K=1.4.

In the said method, the value of percent break is primarily aimed at rod---plate, rod-rod, line---conventional gap such as plate, in esse gap-type and electrode structure in the big metered valve Room, like ball---plate or grading ring---consideration is not given in the sheet separation; To certain electrode structure of confirming, percent break has only a kind of value, does not consider the influence of variablees such as clearance distance and electrode size to the percent break value.The aforementioned calculation method is more coarse, and error is bigger.

The value of percent break K is directly related with the air clear distance, and the size of air clear distance directly has influence on valve Room size, and then influences construction costs.Be assurance equipment and personal safety, said method in use need leave big nargin, has increased construction investment greatly.

In recent years, China's DC transmission engineering is more and more.Engineering design presses for a kind of percent break obtaining value method and the minimum clearance computing method that can consider multiple factors such as valve Room actual gap type and electrode structure, electrode size.

Summary of the invention

The objective of the invention is to propose a kind of based on the straight-wavy valve Room of improving percent break minimum air free distance computation method; Consider gap-type, electrode size, clearance distance, meteorological condition and sea level elevation etc. in the valve Room; Improve percent break through introducing; Utilize the meteorological condition and the sea level elevation modification method of existing comparative maturity, confirm the minimum clearance of straight-wavy valve Room air of safety easily.

The straight-wavy valve Room minimum air free distance computation method based on the improvement percent break that the present invention proposes may further comprise the steps:

(1) establish that the gap-type between the electrical equipment comprises in the straight-wavy valve Room: ball or ring are to plate, pipe bus to plate, ball or ring to pipe bus, pipe bus to pipe bus and valve tower over the ground; For every kind of gap-type; Obtain clearance distance d and electrode size r through actual measurement; Through the switching impulse discharge test, obtain and this clearance distance and the corresponding sparking voltage U of electrode size ₅₀, repeat this step, obtain clearance distance d, electrode size r and sparking voltage U with a kind of gap-type ₅₀Between discrete point combination (d ₁, r ₁, U ₅₀₁), (d ₂, r ₂, U ₅₀₂), (d ₃, r ₃, U ₅₀₃) ... (d _i, r _i, U _50i), wherein i measures number of times;

(2) to above-mentioned each gap-type, with each gap discharge voltage U of following formula match ₅₀And the funtcional relationship between each clearance distance d and the electrode size r, electrode wherein are any in ball, ring, pipe bus or the valve tower:

$U_{50}=d^{\frac{5}{3}}(b_0+b_1\left(\frac{1}{d}\right)+b_2{\left(\frac{1}{d}\right)}^2)(a_0+a_{1}r+a_2{r}^2)$

A wherein ₀, a ₁, a ₂, b ₀, b ₁And b ₂Be respectively coefficient undetermined,

With (d ₁, r ₁, U ₅₀₁), (d ₂, r ₂, U ₅₀₂), (d ₃, r ₃, U ₅₀₃) ... (d _i, r _i, U _50i) in value substitution following formula respectively, calculate coefficient a with least square method ₀, a ₁, a ₂, b ₀, b ₁And b ₂

(3) according to the sparking voltage U of step (2) ₅₀Function expression, obtain the improvement percent break expression formula K under the switching impulse effect:

$K=\frac{(b_0+b_1\frac{1}{d}+b_2{\left(\frac{1}{d}\right)}^2)(a_0+a_{1}r+a_2{r}^2)}{500}$

(4) according to the expression formula K of above-mentioned improvement percent break, calculate the minimum clearance in all types of gaps, concrete grammar is following:

(4-1), set a design margin k according to the requirement of DC power transmission system systems engineering _m, and calculate the relative air density δ under the service condition of the straight-wavy valve Room:

$\mathrm{\δ}=\frac{p}{p_0}\frac{273+t_0}{273+t}$

P wherein ₀Be the atmospheric pressure under the standard state, t ₀Be the temperature under the standard state, p is the air pressure under the service condition of the straight-wavy valve Room, and t is the temperature under the service condition of the straight-wavy valve Room;

(4-2) set two intermediate parameters m and w, the value of two intermediate parameters m and w is 0 during initialization, and defining the atmospheric density correction factor is k ₁, the definition humidity correction factor is k ₂, initial value is established k ₁=1, k ₂=1, and establish initial improvement percent break K=1;

(4-3) calculate the Atmospheric corrections COEFFICIENT K _t, K _t=k ₁k ₂

(4-4) the sparking voltage U of calculated gap _W-corr,

U wherein _wBe the switching impulse insulation tolerance value of the electrical equipment that links to each other with electrode in the straight-wavy valve Room, k _mBe design margin, K _tBe the Atmospheric corrections coefficient, σ is the coefficient of variation of gap discharge voltage, and for switching impulse, σ gets 6%;

(4-5) according to above-mentioned U _W-corr, calculate a clearance distance d:

$d=\sqrt[0.6]{\frac{U_{w-\mathrm{corr}}}{500K}}$

(4-6) according to electrode size r and above-mentioned clearance distance d, calculate and improve percent break K:

$K=\frac{(b_0+b_1\frac{1}{d}+b_2{\left(\frac{1}{d}\right)}^2)(a_0+a_{1}r+a_2{r}^2)}{500}$

(4-7) utilize the K that obtains in the d that obtains in the step (4-5) and the step (4-6), obtain an intermediate parameters g:

$g=\frac{U_{w-\mathrm{corr}}}{500\mathrm{d\δK}}$

(4-8) according to the funtcional relationship in above-mentioned g value and the following table, calculate intermediate parameters m and w;

The funtcional relationship of intermediate parameters m and w and intermediate parameters g

(4-9) according to the m and the w that obtain in the step (4-8), calculate the Atmospheric corrections COEFFICIENT K _t,

k ₁＝δ ^m

k ₂＝k ^w

$k=1+0.01(\frac{d}{\mathrm{\δ}}-11)$

K _t＝k ₁k ₂；

(4-10) the clearance distance d to step (4-5) judges; If when facing twice iteration mutually, the relative difference of d is less than or equal to 0.1%, then stop to calculate; And with this clearance distance d as the minimum air clear distance in the straight-wavy valve Room under these natural conditions; If when facing twice iteration mutually, the relative difference of d is greater than 0.1%, and repeating step (4-5) is to (4-10).

The present invention propose based on the straight-wavy valve Room of improving percent break minimum air free distance computation method, compared with present technology, can take into full account true electrode structure and size and clearance distance in the valve Room to the influence of percent break value.The minimum air clear distance in the straight-wavy valve Room determines the size in the valve Room, can influence the overall cost in the device fabrication difficulty and the straight-wavy valve Room significantly.Confirm the minimum air clear distance in the straight-wavy valve Room according to the present invention, can when guaranteeing equipment operation safety, reduce air clear distance value as far as possible, save construction investment.Computing method of the present invention be primarily aimed at the air clear distance by the switching impulse decision, but the inventive method and principle are suitable equally to lightning impulse.

Embodiment

The straight-wavy valve Room minimum air free distance computation method based on the improvement percent break that the present invention proposes may further comprise the steps:

(1) establish that the gap-type between the electrical equipment comprises in the straight-wavy valve Room: ball or ring are to plate, pipe bus to plate, ball or ring to pipe bus, pipe bus to pipe bus and valve tower over the ground; For every kind of gap-type; Obtain clearance distance d and electrode size r through actual measurement; Through the switching impulse discharge test, obtain and this clearance distance and the corresponding sparking voltage U of electrode size ₅₀, repeat this step, obtain clearance distance d, electrode size r and sparking voltage U with a kind of gap-type ₅₀Between discrete point combination (d ₁, r ₁, U ₅₀₁), (d ₂, r ₂, U ₅₀₂), (d ₃, r ₃, U ₅₀₃) ... (d _i, r _i, U _50i), wherein i measures number of times;

(2) to above-mentioned each gap-type, with each gap discharge voltage U of following formula match ₅₀And the funtcional relationship between each clearance distance d and the electrode size r, electrode wherein are any in ball, ring, pipe bus or the valve tower:

$U_{50}=d^{\frac{5}{3}}(b_0+b_1\left(\frac{1}{d}\right)+b_2{\left(\frac{1}{d}\right)}^2)(a_0+a_{1}r+a_2{r}^2)$

A wherein ₀, a ₁, a ₂, b ₀, b ₁And b ₂Be respectively coefficient undetermined,

With (d ₁, r ₁, U ₅₀₁), (d ₂, r ₂, U ₅₀₂), (d ₃, r ₃, U ₅₀₃) ... (d _i, r _i, U _50i) in value substitution following formula respectively, calculate coefficient a with least square method ₀, a ₁, a ₂, b ₀, b ₁And b ₂

(3) according to the sparking voltage U of step (2) ₅₀Function expression, obtain the improvement percent break expression formula K under the switching impulse effect:

$K=\frac{(b_0+b_1\frac{1}{d}+b_2{\left(\frac{1}{d}\right)}^2)(a_0+a_{1}r+a_2{r}^2)}{500}$

(4) according to the expression formula K of above-mentioned improvement percent break, calculate the minimum clearance in all types of gaps, concrete grammar is following:

(4-1), set a design margin k according to the engine request of DC transmission system _m, and calculate the relative air density δ under the service condition of the straight-wavy valve Room:

$\mathrm{\δ}=\frac{p}{p_0}\frac{273+t_0}{273+t}$

P wherein ₀Be the atmospheric pressure under the standard state, t ₀Be the temperature under the standard state, p is the air pressure under the service condition of the straight-wavy valve Room, and t is the temperature under the service condition of the straight-wavy valve Room;

(4-2) set two intermediate parameters m and w, the value of two intermediate parameters m and w is 0 during initialization, and defining the atmospheric density correction factor is k ₁, the definition humidity correction factor is k ₂, initial value is established k ₁=1, k ₂=1, and establish initial improvement percent break K=1;

(4-3) calculate the Atmospheric corrections COEFFICIENT K _t, K _t=k ₁k ₂

(4-4) the sparking voltage U of calculated gap _W-corr, U wherein _wBe the switching impulse insulation tolerance value of the electrical equipment that links to each other with electrode in the straight-wavy valve Room, k _mBe design margin, K _tBe the Atmospheric corrections coefficient, σ is the coefficient of variation of gap discharge voltage, and for switching impulse, σ gets 6%;

(4-5) according to above-mentioned U _W-corr, calculate a clearance distance d:

$d=\sqrt[0.6]{\frac{U_{w-\mathrm{corr}}}{500K}}$

(4-6) according to electrode size r and above-mentioned clearance distance d, calculate and improve percent break K:

$K=\frac{(b_0+b_1\frac{1}{d}+b_2{\left(\frac{1}{d}\right)}^2)(a_0+a_{1}r+a_2{r}^2)}{500}$

(4-7) utilize the K that obtains in the d that obtains in the step (4-5) and the step (4-6), obtain an intermediate parameters g:

$g=\frac{U_{w-\mathrm{corr}}}{500\mathrm{d\δK}}$

(4-8) according to the funtcional relationship in above-mentioned g value and the following table, calculate intermediate parameters m and w;

The funtcional relationship of intermediate parameters m and w and intermediate parameters g

(4-9) according to the m and the w that obtain in the step (4-8), calculate the Atmospheric corrections COEFFICIENT K _t,

k ₁＝δ ^m

k ₂＝k ^w

$k=1+0.01(\frac{d}{\mathrm{\δ}}-11)$

K _t＝k ₁k ₂；

(4-10) the clearance distance d to step (4-5) judges; If when facing twice iteration mutually, the relative difference of d is less than or equal to 0.1%, then stop to calculate; And with this clearance distance d as the minimum air clear distance in the straight-wavy valve Room under these natural conditions; If when facing twice iteration mutually, the relative difference of d is greater than 0.1%, and then repeating step (4-5) is to (4-10).

Claims (1)

1. one kind based on the straight-wavy valve Room of improving percent break minimum air free distance computation method, it is characterized in that this method may further comprise the steps:

(1) establish that the gap-type between the electrical equipment comprises in the straight-wavy valve Room: ball or ring are to plate, pipe bus to plate, ball or ring to pipe bus, pipe bus to pipe bus and valve tower over the ground; For every kind of gap-type; Obtain clearance distance d and electrode size r through actual measurement; Through the switching impulse discharge test, obtain and this clearance distance and the corresponding sparking voltage U of electrode size ₅₀, repeat this step, obtain clearance distance d, electrode size r and sparking voltage U with a kind of gap-type ₅₀Between discrete point combination (d ₁, r ₁, U ₅₀₁), (d ₂, r ₂, U ₅₀₂), (d ₃, r ₃, U ₅₀₃) ... (d _i, r _i, U _50i), wherein i measures number of times;

(2) to above-mentioned each gap-type, with each gap discharge voltage U of following formula match ₅₀And the funtcional relationship between each clearance distance d and the electrode size r, electrode wherein are any in ball, ring, pipe bus or the valve tower:

$U_{50}=d^{\frac{5}{3}}(b_0+b_1\left(\frac{1}{d}\right)+b_2{\left(\frac{1}{d}\right)}^2)(a_0+a_{1}r+a_2{r}^2)$

A wherein ₀, a ₁, a ₂, b ₀, b ₁And b ₂Be respectively coefficient undetermined,

With (d ₁, r ₁, U ₅₀₁), (d ₂, r ₂, U ₅₀₂), (d ₃, r ₃, U ₅₀₃) ... (d _i, r _i, U _50i) in value substitution following formula respectively, calculate coefficient a with least square method ₀, a ₁, a ₂, b ₀, b ₁And b ₂

(3) according to the sparking voltage U of step (2) ₅₀Function expression, obtain the improvement percent break expression formula K under the switching impulse effect:

$K=\frac{(b_0+b_1\frac{1}{d}+b_2{\left(\frac{1}{d}\right)}^2)(a_0+a_{1}r+a_2{r}^2)}{500}$

(4) according to above-mentioned improvement percent break expression formula K, calculate the minimum clearance in all types of gaps, concrete grammar is following:

(4-1), set a design margin k according to the engine request of DC transmission system _m, and calculate the relative air density δ under the service condition of the straight-wavy valve Room:

$\mathrm{\δ}=\frac{p}{p_0}\frac{273+t_0}{273+t}$

P wherein ₀Be the atmospheric pressure under the standard state, t ₀Be the temperature under the standard state, p is the air pressure under the service condition of the straight-wavy valve Room, and t is the temperature under the service condition of the straight-wavy valve Room;

(4-2) set two intermediate parameters m and w, the value of two intermediate parameters m and w is 0 during initialization, and defining the atmospheric density correction factor is k ₁, the definition humidity correction factor is k ₂, initial value is established k ₁=1, k ₂=1, and establish initial improvement percent break K=1;

(4-3) calculate the Atmospheric corrections COEFFICIENT K _t, K _t=k ₁k ₂

(4-4) the sparking voltage U of calculated gap _W-corr,

U wherein _wBe the switching impulse insulation tolerance value of the electrical equipment that links to each other with electrode in the straight-wavy valve Room, k _mBe design margin, K _tBe the Atmospheric corrections coefficient, σ is the coefficient of variation of gap discharge voltage, and for switching impulse, σ gets 6%;

(4-5) according to above-mentioned U _W-corr, calculate a clearance distance d:

$d=\sqrt[0.6]{\frac{U_{w-\mathrm{corr}}}{500K}}$

(4-6) according to electrode size r and above-mentioned clearance distance d, calculate and improve percent break K:

$K=\frac{(b_0+b_1\frac{1}{d}+b_2{\left(\frac{1}{d}\right)}^2)(a_0+a_{1}r+a_2{r}^2)}{500}$

(4-7) utilize the K that obtains in the d that obtains in the step (4-5) and the step (4-6), obtain an intermediate parameters g:

$g=\frac{U_{w-\mathrm{corr}}}{500\mathrm{d\δK}}$

(4-8) according to the funtcional relationship in above-mentioned g value and the following table, calculate intermediate parameters m and w;

The funtcional relationship of intermediate parameters m and w and intermediate parameters g

(4-9) according to the m and the w that obtain in the step (4-8), calculate the Atmospheric corrections COEFFICIENT K _t,

k ₁＝δ ^m

k ₂＝k ^w

$k=1+0.01(\frac{d}{\mathrm{\δ}}-11)$

K _t＝k ₁k ₂；

(4-10) the clearance distance d to step (4-5) judges; If when facing twice iteration mutually, the relative difference of d is less than or equal to 0.1%, then stop to calculate; And with this clearance distance d as the minimum air clear distance in the straight-wavy valve Room under these natural conditions; If when facing twice iteration mutually, the relative difference of d is greater than 0.1%, and repeating step (4-5) is to (4-10).