CN101621199B - Automatic tuning method of preset arc suppression coil - Google Patents

Abstract

The invention relates to an automatic tuning method of a preset arc suppression coil, which comprises the following steps: further calculating the off tuning degree and the damping ratio of a power grid through measuring the change on the unbalanced voltage of the power grid; measuring the unbalanced voltage at the neutral point of the power grid and a certain line voltage value of the power grid during the normal operation of the power grid, calculating and monitoring the change on the relative unbalance degree of the power grid to judge whether the off tuning degree of the power grid is changed, i.e. whether the power grid requires line delivering and switching operations, and deciding whether the off tuning degree and the damping ratio of the power grid are newly measured; when the off tuning degree and the damping ratio of the power grid are measured, firstly measuring the unbalanced voltages of the power grid, then, controlling a tuned arc suppression coil to increase and output compensating current (electrical susceptance) for the power grid by a controller, and finally, measuring the unbalanced voltage of the power grid and calculating the off tuning current and the damping ratio of the power grid. The arc suppression coil is adjusted according to the measured off tuning current of the power grid to output the compensating current and then the currently running off tuning current of the power grid is further calculated again so as to validate that the currently running tuning current of the power grid is smaller than the setting valve of the off tuning current.

Description

A kind of automatic tuning method of preset arc suppression coil

Technical field

What the present invention relates to is a kind of measurement and control method of technical field of electricity, specifically is the automatic follow-up tuning control technology of neutral point of electric network through arc suppression coil earthing system.

Background technology

During resonant earthed system generation single phase ground fault, the reliability that power distribution network is powered is recovered, helped more improving to the more little fault of extinguishing, help more that helps fault electric arc more of the residual flow of earth fault certainly, therefore, it is high to need the arc suppression coil tuning controller that the certainty of measurement of electrical network earthing capacitance current is tried one's best, and arc suppression coil is moved under near " full compensation " state as far as possible.The existing method of measurement residual voltage maximum method that is used for the control of preset arc suppression coil automatic follow-up tuning, the impedance triangle method, phase place tuning methods etc., they respectively have characteristics, the arc suppression coil that is suitable for different adjustment inductance mode respectively, but they have common defective, it promptly not the earthing capacitance current that accurately measures electrical network, but progressively approach " full compensation " state, therefore, tuning control can not one-time-reach-place, this will increase machinery and transfer sensing mode arc suppression coil (as: adjusting gapped-core type, turn-adjusting) failure rate of TT﹠C system, shorten the life-span of TT﹠C system, and these tuning methods response speed are low, degree of regulation is low.

Summary of the invention

Technical problem: the purpose of this invention is to provide a kind of preset arc suppression coil automatic tuning new method.This method was both accurately measured the power-to-ground capacitance electric current, arc suppression coil is transferred the sense one-time-reach-place, also measure the damping current (real component in the earth fault current) of electrical network simultaneously, help accurately to judge whether damping resistance is working properly, whether size is proper, and then help to improve the fail safe of arc suppression coil earthing system operation; This method is suitable for the tuning control of the preset arc suppression coil of any accent sensing mode, belongs to the general tuning control method of preset arc suppression coil in essence.

Technical scheme: a kind of automatic tuning method of preset arc suppression coil of the present invention may further comprise the steps:

Step a. just at first measures the neutral point unbalance voltage U of electrical network in the very first time of arc suppression coil transmission operation ₀₁A certain line magnitude of voltage U with electrical network _X1,

Step b. control is transferred arc suppression coil to increase " known " offset current Δ I of output _BOr be compensation susceptance increment

Step c is measured neutral point of electric network unbalance voltage U again ₀₂A certain line magnitude of voltage U with electrical network _X2, and calculate the humorous electric current I of taking off of electrical networks by formula 1 and formula 2 _vWith damping current be the real component I of earth fault current _g

Formula 1

Formula 2

In the formula: ${\mathrm{\ΔI}}_B=\mathrm{\Δ}\frac{1}{\mathrm{\ωL}}{U}_N/\sqrt{3};$ $I_v=({\mathrm{\ωC}}_{\mathrm{\Σ}}-1/\mathrm{\ωL})U_N/\sqrt{3};$ $I_g=(g_{\mathrm{\Σ}}+g_L)U_N/\sqrt{3}$

u ₀₁(k) and u ₀₂(k) be respectively neutral point of electric network unbalance voltage U ₀₁And U ₀₂Sampled value; N is the sampling number of a power frequency period T; U _NBe the electrical network rated line voltage; Equivalent inductance value when L is the current output offset current of arc suppression coil; C _∑=C _A+ C _B+ C _C, C _A, C _BAnd C _CBe respectively the electrical network three-phase ground capacitance; g _∑For the relatively total electricity of electrical network three is led; g _LBe arc suppression coil loss equivalent conductance;

Steps d. allow earlier ${\stackrel{\&CenterDot;}{U}}_{01}={\stackrel{\&CenterDot;}{U}}_{02},$ ${\mathrm{<figure-callout\; id="01"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{01}^{*}={\mathrm{<figure-callout\; id="02"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{02}^{*},$ Wherein ${\mathrm{<figure-callout\; id="01"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{01}^{*}=\sqrt{3}{\mathrm{<figure-callout\; id="01"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{01}/{\mathrm{<figure-callout\; id="1"\; label="U\; X"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_X,$ ${\mathrm{<figure-callout\; id="02"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{02}^{*}=\sqrt{3}{\mathrm{<figure-callout\; id="02"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{02}/U_{X2},$ Judge that more whether take off humorous electric current takes off humorous electric current I less than adjusting _Dz, as if take off humorous electric current I greater than adjusting _Dz, then carry out step e; If take off humorous electric current I smaller or equal to adjusting _Dz, then remember U ₀₁ ^*, carry out step f then;

Step e. is according to taking off humorous electric current calculated value I _vAdjust the output offset current, work as I _v" increase " output I during for " just " _vThe offset current of value is worked as I _v" minimizing " output I during for " bearing " _vThe offset current of value, and allow Δ I _B=I _v, and then return and carry out step c, verify the humorous current value I of taking off under the current running status of arc suppression coil once more _vWhether take off humorous current value I less than adjusting _Dz

Step f. measures neutral point of electric network unbalance voltage U ₀₂A certain line magnitude of voltage U with electrical network _X2, judge U ₀₂Whether surpass arc suppression coil action setting value U _0dz1, if do not surpass arc suppression coil action setting value U _0dz1, illustrate that then electrical network normally moves, change step h over to and carry out; If surpass arc suppression coil action setting value U _0dz1, electrical network generation single phase ground fault then is described, damping resistance is excised in control immediately, reduces the residual flow of earth fault, extinguishes fault electric arc, and enters step g;

Step g. after the arc suppression coil action, monitor the neutral point excursion voltage U ₀₂Variation, if U ₀₂〉=U _0dz2, then

Illustrate that electric network single-phase earth fault still exists, continue to monitor the neutral point excursion voltage U ₀₂Variation, if U ₀₂＜U _0dz2, illustrating that then electric network single-phase earth fault disappears, electrical network begins normal operation, and control immediately inserts damping resistance, and tuning controller returns to step f operation; U wherein _0dz2Be the setting value that arc suppression coil stops to move, general U _0dz2〉=U _0dz1

Step h. calculates and monitors the variation of the relative degree of unbalance of electrical network ${\mathrm{\&Delta;U}}_0^{*}={\mathrm{<figure-callout\; id="02"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{02}^{*}-{\mathrm{<figure-callout\; id="01"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{01}^{*},$ Judge thus whether electrical network has throwing, tangent line dataway operation, whether decision remeasures humorous degree of taking off of electrical network and ratio of damping, if ${\mathrm{\&Delta;U}}_0^{*}\&GreaterEqual;\mathrm{\&Delta;}{U}_{0\mathrm{dz}}^{*},$ Δ U wherein _0dz ^*Be relative degree of unbalance increment setting value, the three-phase ground capacitance C of electrical network is described _A, C _BAnd C _CVariation has taken place, promptly taken off humorous degree and change, electrical network has operation, returns to step a; If ${\mathrm{\&Delta;U}}_0^{*}<{\mathrm{\&Delta;U}}_{0\mathrm{dz}}^{*},$ The three-phase ground capacitance C of electrical network is described _A, C _BAnd C _CDo not change, promptly take off humorous degree and do not change, electrical network does not have operation, then carries out step f.

Beneficial effect: the invention provides the tuning new method of a kind of preset arc suppression coil, it is accurately measured the power-to-ground capacitance electric current, the accent sense control of arc suppression coil is settled at one go, this will significantly reduce machinery and transfer sensing mode arc suppression coil (as: adjusting gapped-core type, turn-adjusting) failure rate of TT﹠C system, improve the life-span of TT﹠C system, and, these tuning methods response speed are fast, the degree of regulation height, make arc suppression coil operation under " full compensation " state quickly, the residual flow that helps earth fault reduces, help extinguishing of fault electric arc, help fault from recovering, help improving the reliability of power distribution network power supply; This method is also measured the damping current (real component in the earth fault current) of electrical network simultaneously, helps accurately to judge whether damping resistance is working properly, whether size is proper, helps to improve the fail safe of arc suppression coil earthing system work.This method has advantages such as measuring tuning principle clear thinking, calculate simply, very easy-to-use chip microcontroller, used expense are low.This method is suitable for the tuning control of the preset arc suppression coil of any accent sensing mode, belongs to the general tuning control method of preset arc suppression coil in essence, is applicable to the tuning control of the preset arc suppression coil that different manufacturers produce.

Description of drawings

Fig. 1 be neutral point of electric network through grounding through arc equivalent circuit schematic diagram,

Fig. 2 is tuning control hardware structural representation,

Fig. 3 is tuning Control Software schematic flow sheet.

Embodiment

To achieve these goals, enforcement of the present invention can directly obtain the bus voltage signal and the residual voltage signal of electrical network from the PT secondary side; " pulse " of controller output can be used for the tuning control of arc suppression coils such as " three-phase five-limbs ", and " switching value " can be used for the tuning control of arc suppression coils such as " turn-adjustings ".The tuning controller hardware configuration is seen Fig. 3.

The present invention carries out according to the following steps,

Step a. just at first measures the neutral point unbalance voltage U of electrical network in the very first time of arc suppression coil transmission operation ₀₁A certain line magnitude of voltage U with electrical network _X1, carry out step b then;

Step b. control is transferred arc suppression coil to increase " known " offset current Δ I of output _BOr be compensation susceptance increment

Here increase " known " offset current Δ I of output _BBe not a measured value, it is the value by the control characteristic decision of arc suppression coil under rated operational voltage, and its essence is compensation susceptance increment

As to " turn-adjusting " arc suppression coil, it is arc suppression coil difference between two grades under rated voltage.This value is the characteristic decision of arc suppression coil, is accurately " known " when arc suppression coil dispatches from the factory.Carry out step c then;

Step c is measured neutral point of electric network unbalance voltage U again ₀₂A certain line magnitude of voltage U with electrical network _X2, and calculate the humorous electric current I of taking off of electrical networks by formula 1 and formula 2 _vAnd damping current (real component of earth fault current) I _g

Formula 1

Formula 2

In the formula: ${\mathrm{\&Delta;I}}_B=\mathrm{\&Delta;}\frac{1}{\mathrm{\&omega;L}}{U}_N/\sqrt{3};;$ $I_v=({\mathrm{\&omega;C}}_{\mathrm{\&Sigma;}}-1/\mathrm{\&omega;L})U_N/\sqrt{3};$ $I_g=(g_{\mathrm{\&Sigma;}}+g_L)U_N/\sqrt{3}$

u ₀₁(k) and u ₀₂(k) be respectively neutral point of electric network unbalance voltage U ₀₁And U ₀₂Sampled value; N is the sampling number of a power frequency period T; U _NBe the electrical network rated line voltage; Equivalent inductance value when L is the current output offset current of arc suppression coil $(\frac{1}{\mathrm{\&omega;L}}=\frac{1}{{\mathrm{\&omega;L}}_0}+\mathrm{\&Delta;}\frac{1}{\mathrm{\&omega;L}});$ C _∑=C _A+ C _B+ C _C, C _A, C _BAnd C _CBe respectively the electrical network three-phase ground capacitance; g _∑For the relatively total electricity of electrical network three is led; g _LBe arc suppression coil loss equivalent conductance;

Formula 1 and formula 2 can be derived from following method:

As seen from Figure 1, the U that more than measures ₀₁And U ₀₂Can be expressed from the next:

${\stackrel{\&CenterDot;}{U}}_{01}=-\frac{\frac{1}{r_A}+\mathrm{j\&omega;}{C}_A+{\mathrm{\&alpha;}}^2(\frac{1}{r_B}+\mathrm{j\&omega;}{C}_B)+\mathrm{\&alpha;}(\frac{1}{r_C}+\mathrm{j\&omega;}{C}_C)}{g_{\mathrm{\&Sigma;}}+g_L+j(\mathrm{\&omega;}{C}_{\mathrm{\&Sigma;}}-1/\mathrm{\&omega;}{L}_0)}{\stackrel{\&CenterDot;}{E}}_A$

${\stackrel{\&CenterDot;}{U}}_{02}=-\frac{\frac{1}{r_A}+\mathrm{j\&omega;}{C}_A+{\mathrm{\&alpha;}}^2(\frac{1}{r_B}+\mathrm{j\&omega;}{C}_B)+\mathrm{\&alpha;}(\frac{1}{r_C}+\mathrm{j\&omega;}{C}_C)}{g_{\mathrm{\&Sigma;}}+g_L+j(\mathrm{\&omega;}{C}_{\mathrm{\&Sigma;}}-\frac{1}{{\mathrm{\&omega;L}}_0}-\mathrm{\&Delta;}\frac{1}{\mathrm{\&omega;L}})}{\stackrel{\&CenterDot;}{E}}_A$

In the formula, a=e ^{J2 π/3}C _∑=C _A+ C _B+ C _C $g_{\mathrm{\&Sigma;}}=\frac{1}{r_A}+\frac{1}{r_B}+\frac{1}{r_C};$ $g_L=\frac{1}{R_L};$

A phase phase electromotive force in the electrical network, V.

More than two formulas subtract each other:

${\stackrel{\&CenterDot;}{U}}_{02}-{\stackrel{\&CenterDot;}{U}}_{01}={\stackrel{\&CenterDot;}{U}}_{01}\frac{\mathrm{j\&Delta;}\frac{1}{\mathrm{\&omega;L}}}{g_{\mathrm{\&Sigma;}}+g_L+j({\mathrm{\&omega;C}}_{\mathrm{\&Sigma;}}-\frac{1}{{\mathrm{\&omega;L}}_0}-\mathrm{\&Delta;}\frac{1}{\mathrm{\&omega;L}})}$

Then: $\mathrm{\&omega;}{C}_{\mathrm{\&Sigma;}}-\frac{1}{\mathrm{\&omega;L}}-j(g_{\mathrm{\&Sigma;}}+g_L)=\frac{{\stackrel{\&CenterDot;}{U}}_{01}}{{\stackrel{\&CenterDot;}{U}}_{02}-{\stackrel{\&CenterDot;}{U}}_{01}}\mathrm{\&Delta;}\frac{1}{\mathrm{\&omega;L}}$

The following formula both sides get with multiply by specified phase voltage:

$I_v-{\mathrm{jI}}_g=\frac{{\stackrel{\&CenterDot;}{U}}_{01}}{{\stackrel{\&CenterDot;}{U}}_{02}-{\stackrel{\&CenterDot;}{U}}_{01}}{\mathrm{\&Delta;I}}_B$

Following formula the right is got real part and is got the humorous electric current of taking off of electrical network (earthing capacitance current) I _v, get imaginary part and get damping current (real component in the earth fault current) I _g:

$I_v=\mathrm{Re}\left(\frac{{\stackrel{\&CenterDot;}{U}}_{01}}{{\stackrel{\&CenterDot;}{U}}_{02}-{\stackrel{\&CenterDot;}{U}}_{01}}\right)\&times;{\mathrm{\&Delta;I}}_B=\frac{U_{01}{\mathrm{<figure-callout\; id="02"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{02}\cos \mathrm{\&theta;}-U_{01}^2}{{\mathrm{<figure-callout\; id="02"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{02}^2+U_{01}^2-{2U}_{01}{\mathrm{<figure-callout\; id="02"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{02}\cos \mathrm{\&theta;}}{\mathrm{\&Delta;I}}_B$

$I_B=-\mathrm{lm}\left(\frac{{\stackrel{\&CenterDot;}{U}}_{01}}{{\stackrel{\&CenterDot;}{U}}_{02}-{\stackrel{\&CenterDot;}{U}}_{01}}\right)\&times;{\mathrm{\&Delta;I}}_B=\frac{U_{02}{\mathrm{<figure-callout\; id="01"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{01}\sin \mathrm{\&theta;}}{U_{02}^2+U_{01}^2-{2U}_{02}{\mathrm{<figure-callout\; id="01"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{01}\cos \mathrm{\&theta;}}{\mathrm{\&Delta;I}}_B$

During actual measurement, desirable electrical network a certain when single phase ground fault the phasor (as the line voltage of electrical network) of phase invariant be with reference to phasor, can guarantee two phasors like this

With

When different time was measured, their declinate θ measured accurately errorless.Two phasors

With

Be respectively with respect to this initial phase angle with reference to phasor

With , then: Just can derive thus formula 1 and formula 2.

Steps d. allow earlier ${\stackrel{\&CenterDot;}{U}}_{01}={\stackrel{\&CenterDot;}{U}}_{02},$ ${\mathrm{<figure-callout\; id="01"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{01}^{*}={\mathrm{<figure-callout\; id="02"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{02}^{*},$ Wherein ${\mathrm{<figure-callout\; id="01"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{01}^{*}=\sqrt{3}{\mathrm{<figure-callout\; id="01"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{01}/{\mathrm{<figure-callout\; id="1"\; label="U\; X"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_X,$ ${\mathrm{<figure-callout\; id="02"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{02}^{*}=\sqrt{3}{\mathrm{<figure-callout\; id="02"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{02}/U_{X2},$ Judge that more whether take off humorous electric current takes off humorous electric current I less than adjusting _Dz, as if take off humorous electric current I greater than adjusting _Dz, then carry out step e; If take off humorous electric current I smaller or equal to adjusting _Dz, then remember U ₀₁ ^*, carry out step f then;

Step e. is according to taking off humorous electric current calculated value I _vAdjust the output offset current, work as I _vDuring for " just ", show that electrical network is current and be in " undercompensation " that arc suppression coil should " increase " output I _vThe offset current of value is worked as I _vDuring for " bearing ", show that electrical network is current and be in " overcompensation " that arc suppression coil should " reduce " output I _vThe offset current of value makes arc suppression coil near the operation down of " full compensation " state, allows Δ I then _B=I _v, return and carry out step c, verify that once more arc suppression coil is adjusted offset current output after, take off humorous current value I under the current running status _vWhether take off humorous current value I less than adjusting _Vdz

Step f. measures neutral point of electric network unbalance voltage U ₀₂A certain line magnitude of voltage U with electrical network _X2, judge U ₀₂Whether surpass arc suppression coil action setting value U _0dz1, because the notable attribute of single phase ground fault is the rising of neutral point of electric network unbalance voltage, therefore, if U ₀₂Do not surpass arc suppression coil action setting value U _0dz1, illustrate that then electrical network normally moves, change step h over to and carry out; If surpass arc suppression coil action setting value U _0dz1, illustrating that then single phase ground fault has taken place electrical network, damping resistance is excised in control immediately, reduces the residual flow of earth fault, extinguishes fault electric arc, and enters step g;

Step g. after the arc suppression coil action, the size of neutral point of electric network unbalance voltage is still judges whether electrical network exists the most effective criterion of single phase ground fault, therefore, by monitoring the neutral point excursion voltage U ₀₂Variation can judge accurately whether the single phase ground fault of electrical network disappears.If U ₀₂〉=U _0dz2, illustrate that then electric network single-phase earth fault still exists, continue to monitor the neutral point excursion voltage U ₀₂Variation, if U ₀＜U _0dz2, illustrating that then electric network single-phase earth fault disappears, electrical network begins normal operation, and control immediately inserts damping resistance, to prevent electrical network generation series resonance, " illusory ground connection " phenomenon occurs, and then tuning controller returns to step f operation; U wherein _0dz2Be the setting value that arc suppression coil stops to move, general U _0dz2〉=U _0dz1

Step h. calculates and monitors the variation of the relative degree of unbalance of electrical network $\mathrm{\&Delta;}{U}_0^{*}={\mathrm{<figure-callout\; id="02"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{02}^{*}-{\mathrm{<figure-callout\; id="01"\; label="U"\; filenames="H2009101831548E00021.png"\; state="\{\{state\}\}">U</figure-callout>}}_{01}^{*},$ Judge thus whether the humorous degree of taking off of electrical network changes, whether operation (throwing, tangent line road) is promptly arranged, whether decision remeasures humorous degree of taking off of electrical network and ratio of damping.There are 2 reasons can cause the variation of neutral point of electric network unbalance voltage, the one, the variation of line voltage, the neutral point of electric network unbalance voltage is directly proportional with line voltage; The 2nd, the three-phase ground capacitance C of electrical network _A, C _BAnd C _CVariation has taken place, and then the humorous degree that takes off of electrical network changes, and promptly electrical network has operation.Obviously, last cause can not cause the variation of the relative degree of unbalance of electrical network, has only back one reason can cause the variation of the relative degree of unbalance of electrical network, and therefore, the variation of the relative degree of unbalance of electrical network can accurately reflect the three-phase ground capacitance C of electrical network _A, C _BAnd C _CWhether change, promptly whether electrical network has operation.If $\mathrm{\&Delta;}{U}_0^{*}\&GreaterEqual;{\mathrm{\&Delta;U}}_{0\mathrm{ds}}^{*},$ Δ U wherein _0dz ^*Be relative degree of unbalance increment setting value, the three-phase ground capacitance C of electrical network is described _A, C _BAnd C _CVariation has taken place, and the humorous degree that takes off of electrical network changes, and promptly electrical network has operation (throwing, tangent line road), needs measure humorous degree of taking off of electrical network and ratio of damping again, then returns to step a; If ${\mathrm{\&Delta;U}}_0^{*}<\mathrm{\&Delta;}{U}_{0\mathrm{dz}}^{*},$ The three-phase ground capacitance C of electrical network is described _A, C _BAnd C _CDo not change, promptly take off humorous degree and do not change, electrical network does not have operation, then carries out step f;

Concrete control flow such as Fig. 2.

Claims (1)

1. automatic tuning method of preset arc suppression coil is characterized in that this tuning methods may further comprise the steps:

Step a. just at first measures the neutral point unbalance voltage U of electrical network in the very first time of arc suppression coil transmission operation ₀₁A certain line magnitude of voltage U with electrical network _X1,

Step b. control is transferred arc suppression coil to increase " known " offset current Δ I of output _BOr be compensation susceptance increment

Step c is measured neutral point of electric network unbalance voltage U again ₀₂A certain line magnitude of voltage U with electrical network _X2, and calculate the humorous electric current I of taking off of electrical networks by formula 1 and formula 2 _vWith damping current be the real component I of earth fault current _g

Formula 1

Formula 2

In the formula:

u ₀₁(k) and u ₀₂(k) be respectively neutral point of electric network unbalance voltage U ₀₁And U ₀₂Sampled value; N is the sampling number of a power frequency period T; U _NBe the electrical network rated line voltage; Equivalent inductance value when L is the current output offset current of arc suppression coil; C _∑=C _A+ C _B+ C _C, C _A, C _BAnd C _CBe respectively the electrical network three-phase ground capacitance; g _∑Be electrical network three

Relatively total electricity is led; g _LBe arc suppression coil loss equivalent conductance;

Steps d. allow earlier

Wherein

Judge that more whether take off humorous electric current takes off humorous electric current I less than adjusting _Dz, as if take off humorous electric current I greater than adjusting _Dz, then carry out step e; If take off humorous electric current I smaller or equal to adjusting _Dz, then memory

Carry out step f then;

Step e. is according to taking off humorous electric current calculated value I _vAdjust the output offset current, work as I _v" increase " output I during for " just " _vThe offset current of value is worked as I _v" minimizing " output I during for " bearing " _vThe offset current of value, and allow Δ I _B=I _v, and then return and carry out step c, verify the humorous current value I of taking off under the current running status of arc suppression coil once more _vWhether take off humorous current value I less than adjusting _Dz

Step f. measures neutral point of electric network unbalance voltage U ₀₂A certain line magnitude of voltage U with electrical network _X2, judge U ₀₂Whether surpass arc suppression coil action setting value U _0dz1, if do not surpass arc suppression coil action setting value U _0dz1, illustrate that then electrical network normally moves, change step h over to and carry out; If surpass arc suppression coil action setting value U _0dz1, electrical network generation single phase ground fault then is described, damping resistance is excised in control immediately, reduces the residual flow of earth fault, extinguishes fault electric arc, and enters step g;

Step g. after the arc suppression coil action, monitor neutral point unbalance voltage U ₀₂Variation, if U ₀₂〉=U _0dz2, illustrate that then electric network single-phase earth fault still exists, continue to monitor neutral point unbalance voltage U ₀₂Variation, if U ₀₂＜U _0dz2, illustrating that then electric network single-phase earth fault disappears, electrical network begins normal operation, and control immediately inserts damping resistance, and tuning controller returns to step f operation; U wherein _0dz2Be the setting value that arc suppression coil stops to move, general U _0dz2〉=U _0dz1

Step h. calculates and monitors the variation of the relative degree of unbalance of electrical network

Judge thus whether electrical network has throwing, tangent line dataway operation, whether decision remeasures humorous degree of taking off of electrical network and ratio of damping, if

Wherein

Be relative degree of unbalance increment setting value, the three-phase ground capacitance C of electrical network is described _A, C _BAnd C _CVariation has taken place, promptly taken off humorous degree and change, electrical network has operation, returns to step a; If

The three-phase ground capacitance C of electrical network is described _A, C _BAnd C _CDo not change, promptly take off humorous degree and do not change, electrical network does not have operation, then carries out step f.

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