CN101316036A - Self-adapting three-phase reclosure decision method of ultra-high voltage electric power line with shunt reactor - Google Patents

Abstract

The invention discloses an ultra-high voltage transmission line self-adaptive three-phase recloser judging method with a shunt reactor. The line residual voltage mode component amplitude is taken as criterion and the failure property can be exactly judged before the circuit breakers at two sides of the transmission line are reclosed, thus respectively realizing the quick action of the recloser during the transient failure and the locking of the recloser during the permanent failure. Compared with the prior art, the judging method of the invention avoids the secondary impact on the electric installation and the threatening on the stability of the system caused by that the circuit breaker is reclosed at the permanent failure in three-phase, quickens the closing time during the transient failure, is beneficial for the stability of the system and the continuity of the power supply, can only use a micro-computer protection device to process the sampling data of the voltage at the line termination without adding any devices, affects no action time of the protection and has simple arithmetic.

Description

The self-adapting three-phase reclosure decision method of ultra-high voltage electric power line of band shunt reactor

Technical field

The present invention relates to the automatic reclosing control method of transmission line in the electric power system, particularly related to the implementation method that a kind of transmission line self adaptation three-phase reclosing nature of trouble (permanent fault or transient fault) is judged.

Background technology

The fault that takes place on the overhead transmission line is instantaneity mostly, and overlapping the circuit tripping after the blow-out of fault point is the normal operation of restorable system mutually, therefore, can power the extensive use in high-voltage fence of automatic reclosing technology continually and steadily for ensureing electric power system.Current auto recloser is divided at single-phase fault, single-phase tripping operation, the single-pole reclosing of single-phase coincidence and at heterogeneous fault, the three-phase tripping operation, three three-phase reclosing two classes that coincide, but, no matter which kind of mode, before overlapping in the detection line transient fault or permanent fault did not take place, only be after the tripping of circuit both sides, promptly to overlap through certain time-delay, in case the permanent fault of coinciding with, normal power supply that not only can not recovery system, and the secondary pulse that is caused because of coinciding with fault once more to electric equipment, harm that will be when being short-circuited under the normal operating condition, simultaneously, also may destroy the stability of electric power system paired running, cause system oscillation, even disintegrate.Overlap the harm that causes in order to solve above-mentioned blindness, industry is seeking to avoid coinciding with the method for permanent fault always, at present, aspect single-pole reclosing, had before overlapping and to go out to judge and the practical technique of the adaptive reclose selecting whether to overlap to nature of trouble.

Operating experience shows that two-phase and three-phase shortcircuit account for 20%～30% of transmission line malfunction, though ratio is less, it is bigger than the single-phase impact that causes when coinciding with permanent fault that three-phase coincides with permanent fault, endangers also more serious.Therefore, the demand of before overlapping nature of trouble being judged is more urgent.But, since after the three-phase tripping operation in the circuit extractible information very few, make that the research difficulty of three-phase adaptive reclose is bigger, also do not have so far can practical application method occur.

Summary of the invention

In view of above-mentioned technical problem, the self-adapting three-phase reclosure decision method of ultra-high voltage electric power line that has proposed a kind of with shunt reactor of the present invention, adopt circuit residual voltage mold component amplitude as criterion, before overlapping, transmission line both sides circuit breaker can judge nature of trouble exactly, reclosing block when reclosing quick acting and permanent fault when realizing transient fault respectively, thereby the continuation and the stability of the power supply of assurance system avoid three-phase to coincide with the damage that permanent fault causes electric equipment.

The present invention proposes a kind of self-adapting three-phase reclosure decision method of ultra-high voltage electric power line with shunt reactor, compare by the amplitude of differential mode voltage in the residual voltage after the tripping of detection line three-phase and with setting value, the self adaptation that realizes the three-phase reclosing acts assessment, and this method may further comprise the steps:

Judge whether the circuit both sides three-phase tripping operation takes place;

After the three-phase tripping operation, be judged as three-phase fault, or phase to phase fault:

If three-phase fault, the three-phase voltage instantaneous value U of line taking road one side _A, U _B, U _C, obtain α, β mode voltage U _α, U _βInstantaneous value:

U _α＝U _A-U _B，U _β＝U _A-U _C：

Frequency f with α and β mode voltage _DBe fundamental frequency, computing formula is as follows:

${\mathrm{\&omega;}}_D=\sqrt{\frac{2}{C_1{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20081005385900111.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}}=\mathrm{\&omega;}\&CenterDot;\sqrt{K_{\mathrm{SR}}}$

K _SRBe the shunt reactor compensativity, ω is the power frequency angular frequency, and corresponding fundamental frequency is $f_D=\frac{1}{2\mathrm{\&pi;}}{\mathrm{\&omega;}}_D;$

Obtain the amplitude of α and β mode voltage with the all-wave fourier algorithm, and ask its maximum | U _D|:

|U _D|＝max{|U _A-U _B|，|U _A-U _C|}

Will | U _D| with setting value | U _DZ| make comparisons, if | U _D| can in overlapping setting-up time, continue more than or equal to setting value | U _DZ| continue 1/8～1/4 power frequency cycle, then be judged to be transient fault, after certain time-delay, send the order of three-phase combined floodgate;

Will | U _D| with setting value | U _DZ| make comparisons, if in the reclosing setting-up time, | U _D| can not satisfy all the time greater than lasting 1/8～1/4 the power frequency cycle of setting value, then be judged to be permanent fault, locking three-phase reclosing;

If phase to phase fault, two fault phase voltage instantaneous values of line taking road one side, and obtain the poor of two phase voltages;

Frequency with α and β mode voltage is fundamental frequency f _D, computing formula is:

${\mathrm{\&omega;}}_D=\sqrt{\frac{2}{C_1{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20081005385900111.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}}=\mathrm{\&omega;}\&CenterDot;\sqrt{K_{\mathrm{SR}}},$

Obtain in the two-phase amplitude of damped cycle component in each phase voltage difference with the all-wave fourier algorithm | U _D|, | U _D|=| U _A-U _B|, with setting value | U _DZ| make comparisons, if amplitude | U _D| can in the reclosing setting-up time, continue greater than setting value | U _DZ| 1/8～1/4 power frequency cycle, then be judged to be transient fault, after certain time-delay, send the order of three-phase combined floodgate; If in setting-up time, amplitude | U _D| can not then be judged to be permanent fault, locking three-phase reclosing greater than 1/8～1/4 power frequency cycle of setting value all the time.

According to the reclosing requirement on the extra high voltage network, general 500kV transmission line reclosing setting-up time is about 1S.

The present invention compared with prior art, the beneficial effect of this method is: at first, the present invention has avoided the secondary pulse that electric equipment caused because the circuit breaker three-phase coincides with permanent fault and to the threat of system stability; Secondly, the present invention can quicken closing time, after being judged to be transient fault, the constant time lag that can overlap from the mode of judging constantly additional certain short time delay and needn't wait reclosing to set in advance goes to overlap (in order to guarantee the blow-out of fault point again, this time-delay is bigger usually), can guarantee the continuation of line powering so to greatest extent, also highly beneficial to the stability of system simultaneously; At last, the present invention need not add any device, only need utilize microcomputer protecting device that the sampled data of line scan pickup coil side voltage is handled and get final product, do not influence the operate time of protection, and algorithm is simple.

Description of drawings

The three-phase adaptive reclose realization flow schematic diagram that Fig. 1 proposes for the present invention.

Parameter equivalent model in sets of lines when Fig. 2 is the instantaneity three-phase fault.

Parameter equivalent model in sets of lines when Fig. 3 is permanent three-phase fault.

Embodiment

The invention provides a kind of decision method with shunt reactor extra high voltage network self adaptation three-phase reclosing nature of trouble, more direct is to judge before extra high voltage network three-phase reclosing that what taken place is transient fault, or permanent fault.The present invention by the tripping of detection line three-phase after in the residual voltage differential mode voltage amplitude and compare with setting value, thereby realize the self adaptation action of three-phase reclosing.

Its criterion flow process is as shown in Figure 1: at first, heterogeneous fault takes place on the circuit makes circuit both sides circuit breaker three-phase trip, judge whether the circuit both sides three-phase tripping operation takes place, if three-phase fault (comprising alternate and ground connection), the three-phase voltage instantaneous value of line taking road one side is also obtained the instantaneous value (u of α, β mode voltage _α=u _A-u _B, u _β=u _A-u _C), be fundamental frequency f with the frequency of α and β mode voltage (two mode voltage frequencies are identical, can calculate) then according to line parameter circuit value _D, obtain in the three-phase amplitude of damped cycle component in each phase voltage difference with the all-wave fourier algorithm | U _α|, | U _β|,, choose the maximum among the three | U _D|, with setting value | U _DZ| make comparisons,, after certain time-delay, send out the order of three-phase combined floodgate in 1/8～1/4 power frequency cycle if it can continue then to be judged to be transient fault greater than setting value from a certain moment; If in the reclosing time of setting | U _D| can not then be judged to be permanent fault greater than setting value all the time, locking three-phase reclosing.

Heterogeneous fault takes place on the circuit makes circuit both sides circuit breaker three-phase trip, judge whether the circuit both sides three-phase tripping operation takes place, if phase to phase fault (comprising alternate and ground connection), two fault phase voltage instantaneous values of line taking road one side are also obtained the poor of two phase voltages, and the frequency with α and β mode voltage is fundamental frequency f then _D, obtain in the two-phase amplitude of damped cycle component in each phase voltage difference with the all-wave fourier algorithm | U _D|, with setting value | U _DZ| make comparisons, if amplitude | U _D| can in certain hour (1/8～1/4 power frequency cycle), continue greater than setting value from a certain moment | U _DZ|, then being judged to be transient fault, the order of three-phase combined floodgate is sent out in protection after certain time-delay; If it can not then be judged to be permanent fault greater than setting value all the time in setting-up time, locking three-phase reclosing.

Protected operation equation of the present invention and operating criterion provide as follows:

The angular frequency of α, β mode voltage: ${\mathrm{\&omega;}}_D=\sqrt{\frac{2}{C_1{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20081005385900111.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}}=\mathrm{\&omega;}\&CenterDot;\sqrt{K_{\mathrm{SR}}}---\left(1\right)$

K _SRBe the shunt reactor compensativity, ω is the power frequency angular frequency, and corresponding fundamental frequency is $f_D=\frac{1}{2\mathrm{\&pi;}}{\mathrm{\&omega;}}_D.$

Alternate and the three-phase earth fault of three-phase: | U _D|=max{|u _A-u _B|, | u _A-u _C| (2)

Alternate and the double earthfault (being assumed to be the AB phase) of two-phase: | U _D|=| U _A-U _B| (3)

The transient fault criterion: | U _D| 〉=U _DZ(4)

Below by specific embodiment three-phase adaptive reclose transient fault decision technology scheme of the present invention is described further.

(1). the residual voltage characteristic during the three-phase transient fault

Suppose instantaneity three-phase phase fault takes place in the circuit, behind the circuit breaker trip of circuit both sides, the fault point is through blow-out after a while.Adopt the equivalence of T shape, the parameter equivalent model is as shown in Figure 2 in the tripping sets of lines after the blow-out of fault point.The line distribution capacitance equivalence is the alternate capacitor C of circuit mid point _mWith direct-to-ground capacitance C ₀, the little reactance equivalence of both sides shunt reactor and neutral point is alternate reactance L _mLm and reactance L over the ground _g, the self-impedance of circuit is divided equally in the equivalent capacity both sides.

Take all factors into consideration the energy storage of line distribution capacitance and two ends shunt reactor after the blow-out of fault point, above circuit equivalent model adopted the complex frequency domain analysis, use the nodal method of analysis, at the three-phase residual voltage of circuit m end, mid point and n end totally nine amounts find the solution; After ignoring the influence of line impedance, approximate think every mutually in each point voltage along the line equate, make the equation variable be reduced to three phase voltages; Carry out decoupling zero by triumphant human relations Bel transfer pair equation group, respectively three mode voltages after the conversion are found the solution, and carrying out inverse Laplace transform, to try to achieve the time solution of each modulus of m side residual voltage as follows:

1. zero mode voltage is three-phase voltage sum (U _A+ U _R+ U _C), try to achieve its angular frequency by following formula and be:

${\mathrm{\&omega;}}_0=\sqrt{\frac{2}{C_1{L}_0}}=\mathrm{\&omega;}\&CenterDot;\sqrt{K_{\mathrm{SR}0}}---\left(5\right)$

C ₀Be the zero sequence electric capacity of total track length, L ₀Be shunt reactor reactance, K _SR0Be shunt reactor and the little reactance of the neutral point compensativity to circuit zero sequence electric capacity (direct-to-ground capacitance), ω is the power frequency angular frequency.

As can be seen, zero mode voltage is by the equivalence of shunt reactor equivalent direct-to-ground capacitance (being zero sequence electric capacity) the coupling generation of inductance (being the zero sequence inductance) and circuit over the ground, have nothing to do with the equivalent alternate inductance of shunt reactor and the equivalent alternate electric capacity of circuit, so position of failure point is to its not influence.Take all factors into consideration the attenuation of line impedance to energy storage, it is that a frequency is f ₀The damped cycle component.Because fault moment and tripping operation have determined the energy storage of line capacitance and shunt reactor constantly, so the initial magnitude size of damped cycle component depends on fault moment and tripping operation constantly.Because line resistance is very little, so its time constant that declines is bigger, the rate of decay is slower.

2. α and β mode voltage are respectively the poor (u of two phase voltages _A-u _B, u _A-u _C) considering the attenuation of line impedance to energy storage, they are damped cycle components of same frequency, angular frequency is:

${\mathrm{\&omega;}}_D=\sqrt{\frac{2}{C_1{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20081005385900111.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}}=\mathrm{\&omega;}\&CenterDot;\sqrt{K_{\mathrm{SR}}}---\left(6\right)$

In the following formula, C ₁Be the positive sequence electric capacity of total track length, L ₁Be shunt reactor reactance, K _SRBe the shunt reactor compensativity.

As can be seen, α and β mode voltage are produced by the positive sequence reactance of shunt reactor and the positive sequence capacitive coupling of circuit.Because line resistance is less, so its damping time constant is bigger, the rate of decay is slower.

For instantaneity three-phase earth fault, because three-phase line reliably is connected with the earth in the fault point, so zero mode voltage is zero, α and β mode voltage are not subjected to ground connection influence.

(2). the residual voltage characteristic during the three-phase permanent fault

Suppose ABC three-phase phase fault takes place in the circuit, the fault point exists all the time.Behind each phase circuit breaker trip of circuit both sides, its lumped parameter equivalent model as shown in Figure 3.The fault point is x apart from circuit left side protection mounting points apart from the ratio with total track length, and the left and right sides, fault point circuit all adopts the equivalence of T type.Line distribution capacitance can equivalence be the alternate electric capacity xC of left side, fault point circuit mid point _mWith direct-to-ground capacitance xC ₀And the alternate electric capacity and direct-to-ground capacitance (1-x) C of right side, fault point circuit mid point ₀, the self-impedance of twolink is divided equally in the equivalent capacity both sides.

Because line impedance is much smaller than distributed capacitance and shunt reactor induction reactance, thus when asking for the frequency of each damped cycle component in the analytic process below, ignore the influence of line impedance, approximate think every mutually in each point voltage along the line equal.Because the fault point reliably connects, so three-phase voltage also equates (U _A=U _B=U _C), this moment, circuit alternate electric capacity of equivalence and the alternate inductance of shunt reactor equivalence were all by the fault point short circuit.Adopt the complex frequency domain analysis and line voltage distribution is found the solution, formula is as follows:

$\left\{\begin{array}{c}{U}_0\left(S\right)=[U_{0\mathrm{\&Sigma;}}(0-)C_{0\mathrm{\&Sigma;}}{L}_{0}S+i_{0\mathrm{\&Sigma;}}(0-)L_0]/C_0{L}_0{S}^2+2\\ U_{\mathrm{\&alpha;}}\left(S\right)=0\\ U_{\mathrm{\&beta;}}\left(S\right)=0\end{array}\right.---\left(7\right)$

Zero mode voltage on the circuit in the transient state residual voltage is identical during with transient fault.Can think that whether blow-out and blow-out are irrelevant constantly for content and the fault point of zero mode voltage, both zero mode voltage can not hinder character for some reason and change, and had nothing to do with position of failure point.Because each phase voltage of circuit residual voltage equates, so α, β mold component are zero under the permanent fault situation.

For permanent three-phase earth fault, because three-phase line reliably is connected with the earth in the fault point, so zero mode voltage is zero.

Phase to phase fault is when (comprising alternate and ground connection), its analytical method is identical during with three-phase fault, the result shows, under the different faults character, the feature of the α of circuit residual voltage and β mode voltage is identical during with three-phase fault, difference by asking two fault phase terminal voltages as can be seen, its amplitude is very big during transient fault, its amplitude is zero during permanent fault.

(3). the proposition of three-phase reclosing mold component amplitude criterion

The instantaneity three-phase fault takes place in circuit, and after the blow-out of fault point, the α in the three-phase residual voltage, β mode voltage frequency are f _DThe damped cycle component, its amplitude is very big, it is slower to decay, and can detect by the difference of asking two phase voltages.And α, β mode voltage are zero during permanent fault, only contain the very fast high fdrequency component of decay in the difference of two phase voltages.Therefore, we can be f by the difference medium frequency of two phase terminal voltages in the detection line _DThe amplitude size of damped cycle component judge in the circuit transient fault or permanent fault taken place.

During three-phase (comprising alternate and ground connection) transient fault, after the blow-out of fault point, u _αAnd u _βAmplitude be different, its size and fault moment, tripping operation constantly and blow-out relation is all arranged constantly, but the two can not be zero or very little simultaneously; And the two all is zero during permanent fault.Therefore, we can be with the mode voltage amplitude criterion of amplitude the maximum in the two as self adaptation three-phase reclosing:

|u _D|≥U _DZ

|u _D|＝max{|u _A-u _B|，|u _A-u _C|} (8)

During two-phase (comprising alternate and ground connection) transient fault, after the blow-out of fault point, the amplitude of the difference of two fault phase voltages is very big; And the amplitude of the difference of two fault phase voltages is zero during permanent fault.Therefore, we are with the amplitude of the difference of the two fault phase voltages mode voltage amplitude criterion (is example with the AB phase fault) as self adaptation three-phase reclosing:

|u _D|≥U _DZ

|u _D|＝|u _A-u _B| (9)

Because this criterion is actually " having " and " nothing " of distinguishing a certain damped cycle component, therefore, setting value is as long as consider enough resolution and the noiseproof features of hardware unit.During this criterion of practical application, because f _DCan try to achieve according to line parameter circuit value, we can use fundamental frequency to be f _DThe all-wave fourier algorithm ask for the amplitude of damped cycle component.

Above content only is embodiments of the invention, and its purpose is not the restriction that is used for system and method proposed by the invention, and protection scope of the present invention is as the criterion with claim.Under the situation that does not break away from the spirit and scope of the present invention; those skilled in the art all should drop within protection scope of the present invention its all conspicuous modification or variation about form and details of carrying out under the situation that does not depart from scope and spirit of the present invention.

Claims (2)

1. self-adapting three-phase reclosure decision method of ultra-high voltage electric power line with shunt reactor, compare by the amplitude of differential mode voltage in the residual voltage after the tripping of detection line three-phase and with setting value, realize the self adaptation action judgement of three-phase reclosing, this method may further comprise the steps:

Judge whether the circuit both sides three-phase tripping operation takes place;

After the three-phase tripping operation, be judged as three-phase fault, or phase to phase fault:

If three-phase fault, the three-phase voltage instantaneous value U of line taking road one side _A, U _B, U _C, obtain α, β mode voltage U _β, U _βInstantaneous value:

U _α＝U _A-U _B，U _β＝U _A-U _C；

Frequency f with α and β mode voltage _DBe fundamental frequency, computing formula is as follows:

${\mathrm{\&omega;}}_D=\sqrt{\frac{2}{C_1{L}_1}}=\mathrm{\&omega;}\&CenterDot;\sqrt{K_{\mathrm{SR}}}$

K _SRBe the shunt reactor compensativity, ω is the power frequency angular frequency, and corresponding fundamental frequency is $f_D=\frac{1}{2\mathrm{\&pi;}}{\mathrm{\&omega;}}_D;$

Obtain the amplitude of α and β mode voltage with the all-wave fourier algorithm, and ask its maximum | U _D|:

|U _D|＝max{|U _A-U _B|，|U _A-U _C|}

Will | U _D| with setting value | U _DZ| make comparisons, if | U _D| lasting in can be during reclosing is set more than or equal to setting value | U _DZ| 1/8～1/4 power frequency cycle, then be judged to be transient fault, after certain time-delay, send the order of three-phase combined floodgate;

Will | U _D| with setting value | U _DZ| make comparisons, if in during reclosing is set, | U _D| can not satisfy all the time greater than lasting 1/8～1/4 the power frequency cycle of setting value, then be judged to be permanent fault, locking three-phase reclosing;

If phase to phase fault, two fault phase voltage instantaneous values of line taking road one side, and obtain the poor of two phase voltages;

Frequency with α and β mode voltage is fundamental frequency f _D, computing formula is identical with three-phase fault, for:

${\mathrm{\&omega;}}_D=\sqrt{\frac{2}{C_1{L}_1}}=\mathrm{\&omega;}\&CenterDot;\sqrt{K_{\mathrm{SR}}},$

Obtain in the two-phase amplitude of damped cycle component in each phase voltage difference with the all-wave fourier algorithm | U _D|, | U _D|=| U _A-U _B|, with setting value | U _DZ| make comparisons, if amplitude | U _D| can in the reclosing setting-up time, continue greater than setting value | U _DZ| 1/8～1/4 power frequency cycle, then be judged to be transient fault, after certain time-delay, send the order of three-phase combined floodgate; If in setting-up time, amplitude | U _D| can not then be judged to be permanent fault, locking three-phase reclosing greater than 1/8～1/4 power frequency cycle of setting value all the time.

2. the self-adapting three-phase reclosure decision method of ultra-high voltage electric power line of band shunt reactor as claimed in claim 1 is characterized in that, described reclosing setting-up time value is 1S.

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