CN101777753B - Multi-component recombination current flashy flow judgment method of transformer and block relay - Google Patents

Abstract

The invention discloses a multi-component recombination current flashy flow block relay for identifying excitation flashy flow of a transformer, aiming at solving the problems of differential protection malfunction caused by excitation flashy flow during air delivery and rapid action of differential protection when a turn-to-turn fault occurs. The invention provides a multi-component recombination current flashy flow block relay which consists of sample current selection of the flashy flow, three-time harmonic infeed scheme, an electric scheme of the current harmonic ratio and self-adaptive flashy flow block criteria, wherein the action logic diagram of the relay is shown in the attached figure. The test result indicates that the relay has good sensitivity, safety and rapidness. The invention also discloses a recombination current flashy flow judgment method.

Description

Transformer based is in multicomponent recombination current flashy flow judgment method and blocking relay

Technical field

The present invention relates to Protection Technology tranformer protection field, particularly a kind of inrush current of transformer blocking relay.

Background technology

At present, the differential protection of transformer mainly solves two problems in reality: the one, differentiate magnetizing inrush current and fault current; The 2nd, distinguish external fault and internal fault.The differential protection of transformer can be distinguished external fault and internal fault to a certain extent preferably, but in the identification of magnetizing inrush current, also comes with some shortcomings.

At present, main through the main foundation of identification current waveform as judgement magnetizing inrush current and fault current.In various braking magnetizing inrush current schemes, secondary harmonic brake is relatively ripe and reliable.This method of discrimination is basically all disposed in the protection of main transformer both at home and abroad.

Secondary harmonic brake mainly is divided into two kinds, is respectively " phase-splitting braking " and " or door braking ".

Said " phase-splitting braking " is specially: the second harmonic content of transformer one phase surpasses at 15% o'clock, only brakes this phase.

Said " or door braking " is specially: the second harmonic content of the arbitrary phase of transformer surpasses at 15% o'clock, the braking three-phase.

But all there is defective in these two kinds of modes of braking at present.

" phase-splitting braking " possibly cause differential protection malfunction.Magnetizing inrush current received the influence of switching angle, transformer remanent magnetism and system side when for example the transformer sky filled, and the second harmonic content size of each phase is inequality.Operating experience for many years shows that with test possibly to have a certain second harmonic content mutually lower, therefore adopts the phase-splitting braking to cause differential protection malfunction easily.

" or door braking " possibly cause differential protection tripping or deferred action.For example, Transformer Close when inner single-phase fault, A phase fault for example; B is non-fault phase with C mutually mutually, and possibly there is magnetizing inrush current in the B phase mutually with C, and its second harmonic content is higher, owing to adopt or the door braking, therefore, meeting locking rate of three phase flow is differential, and at this moment, fault phase A also can't export mutually.In addition, if internal fault because of a variety of causes, when causing certain phase second harmonic content higher, possibly cause the differential protection tripping.For example the saturated harmonic wave that will cause of current transformer CT produces, and also can there be harmonic wave in system during fault.

In sum, it still is that " or door braking " all exists defective that the secondary harmonic brake of present magnetizing inrush current adopts " phase-splitting braking ", causes the malfunction and the tripping of transformer differential protection protection easily.

Summary of the invention

Be rapidity and the fail safe that takes into account transformer differential protection, the present invention proposes the multicomponent recombination current flashy flow judgment method of transformer.

Said method comprising the steps of:

(1) carries out the current measurement of each side of transformer through each side current transformer of transformer;

(2) calculate three kinds of sample current of the identification of shoving, and confirm to adopt which sample current to discern,

The sample current (is example with 11 wiring transformers) that following three kinds of differential currents after transformer Δ → Y0 conversion are shoved as identification:

First kind of sample current $\left\{\begin{array}{c}{\stackrel{\·}{I}}_{\mathrm{MA}}-{\stackrel{\·}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\η}}_{Y/\mathrm{\Δ}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\·}{I}}_{\mathrm{NA}}-{\stackrel{\·}{I}}_{\mathrm{NC}})\\ {\stackrel{\·}{I}}_{\mathrm{MB}}-{\stackrel{\·}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\η}}_{Y/\mathrm{\Δ}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\·}{I}}_{\mathrm{NB}}-{\stackrel{\·}{I}}_{\mathrm{NA}})\\ {\stackrel{\·}{I}}_{\mathrm{MC}}-{\stackrel{\·}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\η}}_{Y/\mathrm{\Δ}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\·}{I}}_{\mathrm{NC}}-{\stackrel{\·}{I}}_{\mathrm{NB}})\\ 3{\stackrel{\·}{I}}_0={\stackrel{\·}{I}}_{\mathrm{MA}}+{\stackrel{\·}{I}}_{\mathrm{MB}}+{\stackrel{\·}{I}}_{\mathrm{MC}}\end{array}\right.---\left(1\right)$

Second kind of sample current $\left\{\begin{array}{c}{\stackrel{\·}{I}}_{\mathrm{MA}}+\frac{1}{\sqrt{3}{\mathrm{\η}}_{Y/\mathrm{\Δ}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\·}{I}}_{\mathrm{NA}}-{\stackrel{\·}{I}}_{\mathrm{NC}})\\ {\stackrel{\·}{I}}_{\mathrm{MB}}+\frac{1}{\sqrt{3}{\mathrm{\η}}_{Y/\mathrm{\Δ}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\·}{I}}_{\mathrm{NB}}-{\stackrel{\·}{I}}_{\mathrm{NA}})\\ {\stackrel{\·}{I}}_{\mathrm{MC}}+\frac{1}{\sqrt{3}{\mathrm{\η}}_{Y/\mathrm{\Δ}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\·}{I}}_{\mathrm{NC}}-{\stackrel{\·}{I}}_{\mathrm{NB}})\\ 3{\stackrel{\·}{I}}_0={\stackrel{\·}{I}}_{\mathrm{MA}}+{\stackrel{\·}{I}}_{\mathrm{MB}}+{\stackrel{\·}{I}}_{\mathrm{MC}}\end{array}\right.---\left(2\right)$

The third sample current $\left\{\begin{array}{c}{\stackrel{\·}{I}}_{\mathrm{MA}}+0.5{\stackrel{\·}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\η}}_{Y/\mathrm{\Δ}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\·}{I}}_{\mathrm{NA}}-{\stackrel{\·}{I}}_{\mathrm{NC}})\\ {\stackrel{\·}{I}}_{\mathrm{MB}}+0.5{\stackrel{\·}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\η}}_{Y/\mathrm{\Δ}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\·}{I}}_{\mathrm{NB}}-{\stackrel{\·}{I}}_{\mathrm{NA}})\\ {\stackrel{\·}{I}}_{\mathrm{MC}}+0.5{\stackrel{\·}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\η}}_{Y/\mathrm{\Δ}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\·}{I}}_{\mathrm{NC}}-{\stackrel{\·}{I}}_{\mathrm{NB}})\\ 3{\stackrel{\·}{I}}_0={\stackrel{\·}{I}}_{\mathrm{MA}}+{\stackrel{\·}{I}}_{\mathrm{MB}}+{\stackrel{\·}{I}}_{\mathrm{MC}}\end{array}\right.---\left(3\right)$

In the formula:

Be respectively transformer Y0 side three-phase current;

Be respectively transformer Δ side three-phase current;

Be zero-sequence current; MTA is a Y0 side CT no-load voltage ratio; NTA is a Δ side CT no-load voltage ratio; η _{The Y/ Δ}Be Y0 side and Δ side rated voltage ratio;

Wherein, the three-phase differential current is referred to as big poor differential current in the formula (1), and the three-phase differential current in formula (2), the formula (3) is respectively the first virtual difference stream and the second virtual difference stream;

Employing is the differential modes in both sides with many sides differential conversion; Find the maximum side of absolute value of the jump-value of current sampled value in many sides; An and side that this side is decided to be said both sides differential protection; With the jump-value of current sampled value of all the other sides be decided to be the opposite side of said both sides differential protection with equivalence, name M and ∑-M respectively, as the subscript of electric current.

---suddenly-change sampling value differential current

---the maximum side electric current of the absolute value of jump-value of current sampled value in each side

---all the other side equivalent currents

When 20ms integration , with the said second virtual difference stream as sample current;

When 20ms integration , with the said first virtual difference stream as sample current;

The locking of shoving adopt big poor differential current and according to the above-mentioned virtual difference stream of choosing for two blocking relays that shove of sample current formation " or " logic blocking.

Adopt the reason of two blocking relays that shove to be: differential current is taken into account the differential current waveform of the final differential relay of influence reflection between three-phase and since its cancellation zero-sequence component, can not reflect exciting current truly.Virtual poor stream can reflect exciting current truly.Two blocking relays that shove play complementation well.

(3) calculate the selected sample current per phase

then calculated for each phase of the third harmonic current harmonic ratio increased aid

and after each phase current harmonics compromise than

Wherein: I ₂Be the second harmonic of sample current, I ₁First-harmonic for sample current.

(4) the locking identification equations of shoving is (adopt by mutually calculate):

${\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}<0.1\{\cos \frac{\mathrm{\&pi;}}{3}(\frac{I_0}{I_1}+f\left(\frac{I_1}{I_e}\right))+1\}\frac{1.1}{K}+0.05(1-\frac{1.1}{K})$

In the formula:

I ₀DC component for sample current;

I ₂Second harmonic for sample current;

I ₁First-harmonic for sample current;

I _eRated current for transformer;

is a function, and formula is following:

$f\left(\frac{I_1}{I_e}\right)=C_1(C_2\frac{I_1}{I_e}+1)$

Wherein: C ₁And C ₂Be constant, its span is 0～1.

K is by ∑ Δ i _M(t) Δ i _∑-M(t) and ∑ Δ i _∑ ²(t) coefficient of confirming, span is between 0.1～10.

When not satisfying following formula, think magnetizing inrush current, otherwise think fault current, open transformer differential protection.

The invention also discloses multicomponent recombination current based on the aforementioned method of discrimination blocking relay that shoves, the shove implementation method of blocking relay of said recombination current is following:

(1) calculates the sample current of the locking of shoving

3 kinds of sample current that differential currents identification is shoved after employing transformer Δ → Y0 conversion, three kinds of sample current are respectively (is example with 11 wiring transformers):

First kind of sample current $\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}-{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}-{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}-{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}})\\ 3{\stackrel{\&CenterDot;}{I}}_0={\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}\end{array}\right.---\left(1\right)$

Second kind of sample current $\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}})\\ 3{\stackrel{\&CenterDot;}{I}}_0={\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}\end{array}\right.---\left(2\right)$

The third sample current $\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+0.5{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+0.5{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}+0.5{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}})\\ 3{\stackrel{\&CenterDot;}{I}}_0={\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}\end{array}\right.---\left(3\right)$

In the formula: Be Y0 side three-phase current,

Be Δ side three-phase current, subscript A, B, C represent three-phase;

Be zero-sequence current; MTA is a Y0 side CT no-load voltage ratio; NTA is a Δ side CT no-load voltage ratio; η _{The Y/ Δ}Be Y0 side and Δ side voltage ratio.

Differential current expression formula in the formula (1) is called big poor differential current, and formula (2), formula (3) differential current expression formula are respectively the first virtual difference stream and the second virtual difference stream.

Employing is the differential modes in transformer both sides with many sides of transformer differential conversion; Find the maximum side of absolute value of the jump-value of current sampled value in the many sides of transformer; And it is decided to be a side of said both sides differential protection, the jump-value of current sampled value and the equivalence of all the other sides is decided to be the opposite side of said both sides differential protection.Name M and ∑-M respectively, as the subscript of electric current.

---suddenly-change sampling value differential current

---the maximum side electric current of the absolute value of jump-value of current sampled value in each side

---all the other side equivalent currents.

When 20ms integration

; The second virtual difference is flowed as sample current

When 20ms integration

, with the first virtual difference stream as sample current.Wherein m is a coefficient, and span is 1～10.

The locking of shoving adopt big poor differential current and according to the above-mentioned virtual difference stream of choosing for two blocking relays that shove of sample current formation " or " logic blocking.

Big poor differential current is adopted in the locking of shoving and two blocking relays that shove constituting for sample current according to the above-mentioned virtual difference stream of choosing " or " reason of logic blocking is: differential current is taken into account the differential current waveform that 3 alternate influences reflect final differential relay; Since its cancellation zero-sequence component, can not reflect exciting current truly.The attempt of virtual difference stream reflects exciting current truly.Two blocking relays that shove play complementation well.

(2) calculate the sample current harmonics ratio

then calculated for each phase of the third harmonic current harmonic ratio increased aid

Wherein

preferably obtains by following formula:

${\left(\frac{I_2}{I_1}\right)}_z\&DoubleLeftArrow;\frac{I_2}{I_1}+\frac{{\left[\frac{I_3}{I_1}\right]}_{\mathrm{MAX}}}{1+k\frac{I_2}{I_1}}---\left(4\right)$

In the formula: I ₃Be the triple-frequency harmonics of sample current, For triple-frequency harmonics in the three-phase than maximum, k is by ∑ Δ i _M(t) Δ i _∑-M(t) and ∑ Δ i _∑ ²(t) confirm to help and increase coefficient, the span 0.1～200 of k.

(3) the sample current harmonic ratio is preferably compromised by following mode:

At first; The current harmonics that step (2) is calculated sorts by size than : when

has only as

(this value can be adjusted at 0.1-1) mutually with

, just adopt compromise;

Compromise is again an assignment, that is:

${\left({\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}\right)}_{\mathrm{MAX}}\&DoubleLeftArrow;{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MAX}}$

${\left({\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}\right)}_{\mathrm{MID}}\&DoubleLeftArrow;{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MID}}+n\left[{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MAX}}{-\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MID}}\right]$

${\left({\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}\right)}_{\mathrm{MIN}}\&DoubleLeftArrow;{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MIN}}+n\left[{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MAX}}{-\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MIN}}\right]$

In the formula: n=0.05f (t);

F (t) is the function of time; When t≤180ms,

During t＞180ms, f (t)=0.

T is the time, and unit is ms.

Wherein,

is the current harmonics ratio after compromising.

The characteristic quantity of the magnetizing inrush current after the employing assignment is discerned magnetizing inrush current by calculating mutually.

(4) the multicomponent recombination current locking of shoving

Formula is following:

${\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}<0.1\{\cos \frac{\mathrm{\&pi;}}{3}(\frac{I_0}{I_1}+f\left(\frac{I_1}{I_e}\right))+1\}\frac{1.1}{K}+0.05(1-\frac{1.1}{K})---\left(5\right)$

In the formula:

I ₀DC component for sample current;

I ₂Second harmonic for sample current;

I ₁First-harmonic for sample current;

I _eRated current for transformer;

is a function, and formula is following:

$f\left(\frac{I_1}{I_e}\right)=C_1(C_2\frac{I_1}{I_e}+1)$

Wherein: C ₁And C ₂Be constant, its span is 0～1.

K is by ∑ Δ i _M(t) Δ i _∑-M(t) and ∑ Δ i _∑ ²(t) coefficient of confirming, span is between 0.1～10.

When not satisfying following formula, think magnetizing inrush current, otherwise think fault current, open transformer differential protection.

(5) latching logic

Differential current is shoved the blocking relay realization by the phase locking, has solved the transformer sky and has filled in the slow problem of failure transformer responsiveness, does not reduce the reliability of its differential protection simultaneously.

Description of drawings

Fig. 1 is the typical magnetizing inrush current waveform of transformer;

Fig. 2 is the differentiation flow chart of the inventive method;

Fig. 3 is the building-block of logic of braking magnetizing inrush current of the present invention.

Embodiment

For make above-mentioned purpose of the present invention, feature and advantage can be more obviously understandable, through embodiment technical scheme of the present invention done detailed explanation below in conjunction with accompanying drawing.

In order to make those skilled in the art's embodiment of the present invention better, at first introduce several basic conceptions.

Referring to Fig. 1, this figure is the typical magnetizing inrush current waveform of transformer.

The as can be seen from Figure 1 several characteristic amount of waveform: aperiodic component, be interrupted, wave distortion.

Wherein, can find out by the negative semiaxis that waveform major part among Fig. 1 is positioned at the longitudinal axis, rather than evenly distribute aperiodic at positive and negative semiaxis.Harmonic wave can find out that desirable crest should be an arc from waveform, seamlessly transits, and present waveform point and being interrupted, this is mainly caused by harmonic wave.

In the prior art only with the second harmonic of each phase criterion as each phase braking magnetizing inrush current; Easy like this malfunction and the tripping that causes transformer differential protection, and the present invention considers the criterion of blocking relay as braking magnetizing inrush current of shoving that a plurality of current components of magnetizing inrush current are formed.

Concrete implementation method is following:

(1) the shove sample current of locking

Because the Y side all appears in magnetizing inrush current and TA saturation problem, keep the primitiveness of Y side electric current very important.This programme adopts 3 kinds of sample current (is example with 11 wiring transformers) that differential current identification is shoved after Δ → Y0 conversion.Δ → Y0 conversion $\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}-{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}-{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}-{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}})\\ 3{\stackrel{\&CenterDot;}{I}}_0={\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}\end{array}\right.---\left(1\right)$

Δ → Y0 conversion $\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}})\\ 3{\stackrel{\&CenterDot;}{I}}_0={\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}\end{array}\right.---\left(2\right)$

Δ → Y0 conversion $\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+0.5{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+0.5{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}+0.5{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}})\\ 3{\stackrel{\&CenterDot;}{I}}_0={\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}\end{array}\right.---\left(3\right)$

In the formula:

Be Y0 side three-phase current;

Be Δ side three-phase current;

Be zero-sequence current; Be zero-sequence current; MTA is a Y0 side CT no-load voltage ratio; NTA is a Δ side CT no-load voltage ratio; η _{The Y/ Δ}Be Y0 side and Δ side voltage ratio.

Formula (1) is referred to as big poor differential current, and formula (2), formula (3) are referred to as the first virtual difference stream and the second virtual difference stream respectively.

Employing is the differential modes in both sides with many sides differential conversion, finds the maximum side of absolute value of the jump-value of current sampled value in many sides, and this side is decided to be a side, and the sampled value equivalence of all the other sides is decided to be opposite side.Name M and ∑-M respectively, as the subscript of electric current.

---suddenly-change sampling value differential current

---the maximum side electric current of the absolute value of jump-value of current sampled value in each side

---all the other side equivalent currents

Virtual difference stream adopts (3) formula when 20ms integration

, and virtual difference stream adopts (2) formula when 20ms integration

.Wherein m is a coefficient, and span is 1～10.

The locking of shoving adopt big poor differential current and according to the above-mentioned virtual difference stream of choosing for two blocking relays that shove of sample current formation " or " logic blocking.

Big poor differential current is adopted in the locking of shoving and two blocking relays that shove constituting for sample current according to the above-mentioned virtual difference stream of choosing " or " reason of logic blocking is: differential current is taken into account the differential current waveform that 3 alternate influences reflect final differential relay; Since its cancellation zero-sequence component, can not reflect exciting current truly.The attempt of virtual difference stream reflects exciting current truly.Two blocking relays that shove play complementation well.

(2) 3 subharmonic help and increase scheme:

Help the formula that increases following:

${\left(\frac{I_2}{I_1}\right)}_z\&DoubleLeftArrow;\frac{I_2}{I_1}+\frac{{\left[\frac{I_3}{I_1}\right]}_{\mathrm{MAX}}}{1+k\frac{I_2}{I_1}}---\left(4\right)$

In the formula: I ₃Be the triple-frequency harmonics of sample current,

For triple-frequency harmonics in the three-phase than maximum, k increases coefficient for helping, span is 0.1～200.

(3) half-way house of

At first;

of the three-phase that step (2) is calculated sorts by size: when

had only as

(can adjust in the scope at 0.1-1) mutually with

, just employing was compromised;

Compromise is again an assignment, that is:

${\left({\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}\right)}_{\mathrm{MAX}}\&DoubleLeftArrow;{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MAX}}$

${\left({\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}\right)}_{\mathrm{MID}}\&DoubleLeftArrow;{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MID}}+n\left[{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MAX}}{-\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MID}}\right]$

${\left({\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}\right)}_{\mathrm{MIN}}\&DoubleLeftArrow;{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MIN}}+n\left[{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MAX}}{-\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MIN}}\right]$

In the formula: n=0.05f (t);

F (t) is the function of time; When t≤180ms,

During t＞180ms, f (t)=0.

T is the time, and unit is ms.

Wherein,

is the current harmonics ratio after compromising.

The characteristic quantity of the magnetizing inrush current after the employing assignment is discerned magnetizing inrush current by calculating mutually.

(4) the multicomponent recombination current locking criterion of shoving

Formula is following:

${\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}<0.1\{\cos \frac{\mathrm{\&pi;}}{3}(\frac{I_0}{I_1}+f\left(\frac{I_1}{I_e}\right))+1\}\frac{1.1}{K}+0.05(1-\frac{1.1}{K})---\left(5\right)$

In the formula: I ₀DC component for sample current;

I ₂Second harmonic for sample current;

I: be the first-harmonic of sample current;

I _eRated current for transformer;

is a function, and formula is following:

$f\left(\frac{I_1}{I_e}\right)=C_1(C_2\frac{I_1}{I_e}+1)$

Wherein: C ₁And C ₂Be constant, its span is 0～1.

K is by ∑ Δ i _M(t) Δ i _∑-M(t) and ∑ Δ i _∑ ²(t) coefficient of confirming, span is between 0.1～10.

When not satisfying following formula, think magnetizing inrush current, otherwise think fault current, open transformer differential protection.

(5) latching logic

Many components recombination current of the present invention shoves the blocking relay realization by the phase locking.Referring to Fig. 2, Fig. 3 (please use literal to describe in detail, Fig. 2,3 content).

Many components recombination current provided by the invention blocking relay that shoves; Choosing of sample current for the locking of shoving confirmed; And aperiodic component, secondary, triple-frequency harmonics in the characteristic of the exciting current of transformer have carried out rational mathematical expression, simultaneously because each magnetic coupling relation between has mutually proposed the half-way house of harmonic wave locking.Taking all factors into consideration sky at last fills with empty filling in the differentiation of failure transformer and has proposed the operating criterion relevant with the transformer rated current.This invention realizes the phase-splitting locking, has solved the transformer sky and has filled in the slow problem of failure transformer responsiveness, does not reduce the reliability of its differential protection simultaneously.

Claims (5)

1. the multicomponent recombination current blocking method that shoves in the transformer differential protection, the reliable locking when guaranteeing to solve the no-load transformer charging can be opened differential relay simultaneously fast when sky fills failure transformer, and said blocking method may further comprise the steps:

(1) gathers each side electric current of transformer and sudden change amount electric current through current transformer;

(2) the big poor differential current of calculating transformer three-phase and the first virtual difference stream or the second virtual difference stream are as the sample current of two kinds of lockings that are used to shove respectively, and wherein the first virtual difference stream does not comprise zero-sequence component, and the second virtual difference stream comprises zero-sequence component;

(3) become both sides differential many sides of transformer differential conversion, the maximum side of absolute value that is about to the jump-value of current sampled value in the many sides of transformer is as the differential end in both sides, and the suddenly-change sampling value and the equivalence of all the other sides of transformer is decided to be the differential other end in both sides,

When 20ms integration

uses the second virtual difference stream after transformer Δ → Y0 conversion as sample current;

When 20ms integration

uses the first virtual difference stream after transformer Δ → Y0 conversion as sample current;

Wherein,

Δ i _∑(t)---the suddenly-change sampling value differential current,

Δ i _M(t)---the maximum side electric current of the absolute value of jump-value of current sampled value in each side,

Δ i _∑-M(t)=Δ i _∑(t)-Δ i _M(t)---all the other side equivalent currents, be said all the other sides of transformer suddenly-change sampling value and, m is a coefficient, span is 1～10;

(4) calculate big poor differential current, and the current harmonics ratio of each phase of the first virtual difference stream or the second virtual difference stream

I wherein ₂Be the second harmonic of sample current, I ₁First-harmonic for sample current; And then the triple-frequency harmonics that calculates each phase helps the current harmonics ratio that increases

With the current harmonics ratio after each compromise mutually

(5) by calculating mutually; When said each current harmonics after compromising mutually than

during satisfied following formula, open this phase transformer differential protection; When being enough to down formula, think to shove this phase differential protection of locking when discontented:

${\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}<0.1\{\cos \frac{\mathrm{\&pi;}}{3}(\frac{I_0}{I_1}+f\left(\frac{I_1}{I_e}\right))+1\}\frac{1.1}{K}+0.05(1-\frac{1.1}{K})$

In the formula: is the direct current biasing ratio;

I ₀DC component for sample current;

I ₂Second harmonic for sample current;

I ₁First-harmonic for sample current;

I _eRated current for transformer;

The span 0.1～10 of K;

is a function, and formula is following:

$f\left(\frac{I_1}{I_e}\right)=C_1(C_2\frac{I_1}{I_e}+1)$

Wherein: C ₁And C ₂Be constant, its span is 0～1.

2. the blocking method that shoves according to claim 1 is characterized in that: when first, second virtual difference of calculating flows, Transformer Winding triangle side current conversion to star side is calculated.

3. the blocking method that shoves according to claim 2 is characterized in that: adopt following formula to calculate said first, second virtual current after transformer Δ → Y0 conversion:

The first virtual difference stream $\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{T/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}})\\ 3{\stackrel{\&CenterDot;}{I}}_0={\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}\end{array}\right.$

The second virtual difference stream $\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+0.5{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+0.5{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{Y/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NA}})\\ {\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}+0.5{\stackrel{\&CenterDot;}{I}}_0+\frac{1}{\sqrt{3}{\mathrm{\&eta;}}_{T/\mathrm{\&Delta;}}}\frac{\mathrm{NTA}}{\mathrm{MTA}}({\stackrel{\&CenterDot;}{I}}_{\mathrm{NC}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{NB}})\\ 3{\stackrel{\&CenterDot;}{I}}_0={\stackrel{\&CenterDot;}{I}}_{\mathrm{MA}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MB}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{MC}}\end{array}\right.$

In the formula:

Be respectively transformer Y0 side three-phase current; Be respectively transformer Δ side three-phase current;

Be zero-sequence current; MTA is a Y0 side CT no-load voltage ratio; NTA is a Δ side CT no-load voltage ratio; η _{The Y/ Δ}Be Y0 side and Δ side rated voltage ratio.

4. the blocking method that shoves according to claim 3 is characterized in that: said triple-frequency harmonics helps the current harmonics that increases to adopt following computing formula than

:

${\left(\frac{I_2}{I_1}\right)}_z\&DoubleLeftArrow;\frac{I_2}{I_1}+\frac{{\left[\frac{I_3}{I_1}\right]}_{\mathrm{MAX}}}{1+k\frac{I_2}{I_1}}$

Wherein, I ₃Be the triple-frequency harmonics of sample current,

For triple-frequency harmonics in the three-phase than maximum, k increases coefficient for helping, span is 0.1～200.

5. the blocking method that shoves according to claim 4 is characterized in that: under following situation, current harmonics is than further compromising in the following manner:

Triple-frequency harmonics to three-phase helps the current harmonics that increases to sort by size than

:

when having only as

mutually with

; Wherein m1 is a constant; Span is 0.1～1, just adopts compromise;

Compromise is again an assignment, that is:

${\left({\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}\right)}_{\mathrm{MAX}}\&DoubleLeftArrow;{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MAX}}$

${\left({\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}\right)}_{\mathrm{MID}}\&DoubleLeftArrow;{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MID}}+n[{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MAX}}-{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MID}}]$

${\left({\left(\frac{I_2}{I_1}\right)}_{\mathrm{zz}}\right)}_{\mathrm{MIN}}\&DoubleLeftArrow;{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MIN}}+n[{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MAX}}-{\left({\left(\frac{I_2}{I_1}\right)}_z\right)}_{\mathrm{MIN}}]$

In the formula: n=0.05f (t);

F (t) is the function of time; When t≤180ms,

During t＞180ms, f (t)=0,

T is the time, and unit is ms,

Wherein,

is the current harmonics ratio after compromising.

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