CN101931212A - Transformer self-adaptive protector and protection method thereof - Google Patents

Abstract

The invention discloses a transformer self-adaptive protector and a protection method thereof. The protector comprises a quick-acting unit, a fault component unit, a zero-load switching-in unit and a parameter identification and threshold value setting unit, wherein the quick-acting unit protects criteria to set most serious external faults and can eliminate serious faults in a high speed; the fault component unit uses fault component information to improve the protection sensitivity and protects the correct identification of internal weak faults; the zero-load switching-in unit ensures the reliability and the sensitivity only when a transformer is subject to zero-load switching-in; and the identification parameter comprises the leakage inductance of a transformer winding, and the identification result is used for realizing the update of protection parameters and the on-line setting of threshold values, thereby ensuring the protection reliability and sensitivity. The transformer self-adaptive protection scheme based on the equivalent equation principle can meet the relay protection requirements for reliability, selectivity, sensitivity and quick action by the mutual matching of all the units.

Description

A kind of transformer self-adaptive protector and guard method thereof

Technical field:

The invention belongs to field of power, relate to a kind of implementation method of electric system protection device, be particularly suitable for transformer station institute's linchpin transformer is protected configuration and fault distinguishing.

Background technology:

Power transformer is the hinge equipment in the electric power system, plays a part energy and voltage transitions in whole electric power system.Therefore can transformer safe and stable operation directly have influence on the safety and stablization of whole electric power system.Protective relaying device as electric power system " the first line of defence " will play crucial effects therein.Differential protection is the main protection of power transformer always, and it has the advantages that based on Kirchhoff's current law (KCL) principle is simple, highly sensitive, selectivity is good.But transformer is the electric original paper that each winding is linked together by magnetic circuit, and it has no longer satisfied Kirchhoff's current law (KCL) in essence.When no-load transformer combined floodgate or external fault excision, the inner magnetizing inrush current that produces of transformer may reach more than 8 times of rated current, thereby makes differential protection misoperation.

For a long time; for the transformer main protection; the single always configuration of differential protection; be difficult to satisfy relaying protection " four property "---the requirement of reliability, selectivity, quick-action and sensitivity; especially aspect reliability and sensitivity; the differential protection of single configuration all is difficult to guarantee from principle still is practical application, and the performance factor of China's tranformer protection still was in reduced levels this problem just has been described in recent years.In recent years; the protection worker puts into a large amount of energy in the exploration of transformer new principle and the research; wherein fully utilize each side electric current and voltage information of transformer and set up the protection philosophy of the equivalent equation model of transformer, become a focus of numerous transformer new principle research gradually.

But; the common issue with that exists based on the tranformer protection principle of electric current and voltage information is the threshold value difficulty of adjusting, therefore how to make up simple protection criterion and according to transformer nameplate parameter or normal service data realize threshold value flexibly convenient adjusting be based on the subject matter that electric current and voltage information new principle need solve.A new principle is fought separately simultaneously; single configuration; so more highlight in the short slab and the inferior position that satisfy in the relaying protection " four property " comprehensively; the present invention is just on this basis by comprehensive utilization and organic assembling quick-action unit; the fault component unit; idle-loaded switching-on unit and parameter identification updating block are realized the tranformer protection adaptation scheme, embody the self adaptation of complete malfunction, the self adaptation of threshold value and the self adaptation of winding parameter.Simultaneously, thoroughly break away from the magnetizing inrush current influence, can finely satisfy relaying protection " four property "---the requirement of reliability, selectivity, quick-action and sensitivity based on the tranformer protection of equivalent equation principle.

Summary of the invention:

The invention provides a kind of tranformer protection adaptive guard scheme, use this method can break away from the influence of magnetizing inrush current, can correctly go to distinguish in the district and external area error, and have very high sensitivity based on equivalent equation principle; For the transformer that catastrophe failure takes place in the district, realize the tranformer protection adaptation scheme by fully utilizing four elementary cells, satisfy relaying protection " four property "---the requirement of reliability, selectivity, quick-action and sensitivity.For achieving the above object, the technical solution used in the present invention is:

The objective of the invention is to overcome the shortcoming of above-mentioned prior art, a kind of transformer self-adaptive protector is provided, this device comprises quick-action unit, fault component unit, idle-loaded switching-on unit, parameter identification and the threshold value unit of adjusting.

A kind of guard method of transformer self-adaptive protector, according to following steps:

1. protective device is set the nameplate parameter of protected transformer: short-circuit voltage u after electrifying startup _k%, short circuit loss p _k%, transformer rated capacity S _b, transformer rated voltage U _b, rated current I _b, transformer nominal transformation ratio n _B

2. gather the former limit of transformer three-phase winding voltage current data u in real time _1A, u _1B, u _1C, i _1A, i _1B, i _1C, secondary three-phase winding voltage current data u _2A, u _2B, u _2C, i _2A, i _2B, i _2C, judge according to each side current data sudden change amount of transformer whether protection component starts;

3. protection utilizes catastrophe failure in the transformer quick-action protection component quick identification tranformer protection district after starting, and operate time of protection increases with the fault order of severity and reduces; If the action of quick-action protection component, tripping operation excision fault, package unit involution simultaneously; When quick-action element does not move, judge that by transformer secondary winding current amplitude before differentiating the protection startup transformer is in idle-loaded switching-on state or load operation conditions;

4. if this moment, transformer was in the idle-loaded switching-on state, then protection adopts the frequency domain protection component to judge whether troubles inside the sample space of transformer, if then trip signal excision fault is sent in protection, 2. the package unit involution then returns step if not simultaneously;

5. if transformer is in load operation conditions, then protection adopts the fault component protection component to judge whether troubles inside the sample space of transformer, if then trip signal excision fault, package unit involution are simultaneously sent in protection; Then do not show generation tranformer protection external area error if be judged as troubles inside the sample space; this time zone outwash is hit electric current and may the winding of transformer be exerted an influence; therefore enter parameter identification more new element protection parameter and action protection threshold value are carried out real-time update, return step and 2. gather next each side electric current and voltage information of transformer constantly again.

The inventive method need be obtained each side electric current and voltage data of transformer simultaneously; utilize the transformer equivalent circuit model; row write the basic equivalent loop equation of transformer, based on the equivalent loop equation of fault component and the equivalent loop equation frequency domain under, obtain tranformer protection principle by top three transformers equivalence equation based on equivalent equation.Consideration winding parameter sum of errors transformer errors etc. are to the influence of equivalent equation; make a concrete analysis of the amount of unbalance of each operation equation; and amount of unbalance estimated; the result is a foundation with estimation; guaranteeing under the prerequisite that transformer reliably is failure to actuate, obtaining under the time domain under the tranformer protection criterion, time domain based on the equivalent equation of full dose when no-load transformer closes a floodgate under the tranformer protection criterion of the equivalent equation of fault component and the frequency domain protection criterion based on equivalent equation.In addition, by to Transformer Winding resistance and leakage inductance on-line identification, real-time update protection parameter and threshold value guarantee the reliability and the sensitivity of protection action.

Description of drawings:

Accompanying drawing 1 is for implementing the particular flow sheet based on the transformer self-adaptive protection scheme of equivalent equation principle;

Accompanying drawing 2 is Y ₀/ Y ₀The three-phase transformer model of wiring;

Accompanying drawing 3 is Y ₀The three-phase transformer model of/Δ wiring.

The adaptively selected schematic diagram of accompanying drawing 4 protection criterions.

Embodiment:

Below in conjunction with accompanying drawing the present invention is done and to describe in further detail:

The present invention is about the technical scheme of three-phase two winding transformer model:

Shown in accompanying drawing 2 and accompanying drawing 3, for Y ₀/ Y ₀And Y ₀The three-phase transformer model of/Δ wiring has:

The former limit of three-phase two winding transformer winding voltage equation is:

The equivalent equation in secondary voltage loop is

In the formula, u _1j, u _2jBe each phase winding phase voltage of former secondary, i _1j, i _2jBe each phase winding phase current of former secondary, ψ _MjBe the magnetic linkage of winding linkage, r _1j, r _2jAnd L _1j, L _2jBe former secondary each phase winding resistance and leakage inductance, j=A, B, C here.Utilize the former and deputy polygonal voltage loop equation of transformer (1), (2), cancellation mutual inductance magnetic linkage, thus only comprised the equivalent equation (3) of former and deputy polygonal voltage and electric current:

$\left\{\begin{array}{c}0=(u_{1A}-{\mathrm{<figure-callout\; id="1A"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{1A}{i}_{1A}-{\mathrm{<figure-callout\; id="1A"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1A}\frac{{\mathrm{di}}_{1A}}{\mathrm{dt}})-n_T(u_{2A}-{\mathrm{<figure-callout\; id="2A"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{2A}{i}_{2A}-{\mathrm{<figure-callout\; id="2A"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{2A}\frac{{\mathrm{di}}_{2A}}{\mathrm{dt}})\\ 0=(u_{1B}-{\mathrm{<figure-callout\; id="1B"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{1B}{i}_{1B}-{\mathrm{<figure-callout\; id="1B"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1B}\frac{{\mathrm{di}}_{1B}}{\mathrm{dt}})-n_T(u_{2B}-{\mathrm{<figure-callout\; id="2B"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{2B}{i}_{2B}-{\mathrm{<figure-callout\; id="2B"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{2B}\frac{{\mathrm{di}}_{2B}}{\mathrm{dt}})\\ 0=(u_{1C}-{\mathrm{<figure-callout\; id="1C"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{1C}{i}_{1C}-{\mathrm{<figure-callout\; id="1C"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1C}\frac{{\mathrm{di}}_{1C}}{\mathrm{dt}})-n_T(u_{2C}-{\mathrm{<figure-callout\; id="2C"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{2C}{i}_{2C}-{\mathrm{<figure-callout\; id="2C"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{2C}\frac{{\mathrm{di}}_{2C}}{\mathrm{dt}})\end{array}\right.---\left(3\right)$

As can be seen, it is following no matter which kind of state transformer operates in, and only otherwise internal fault takes place, all set up by the equivalent equation that winding port electric current and voltage data and winding parameter obtain.When transformer generation internal fault, because the winding parameter of transformer changes, also there is fault component in the port voltage electric current, makes formula (4) no longer set up, and whether this can become Rob Roy to judge whether transformer breaks down by judging this equation.So, order:

$\left\{\begin{array}{c}{K}_A=(u_{1A}-{\mathrm{<figure-callout\; id="1A"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{1A}{i}_{1A}-{\mathrm{<figure-callout\; id="1A"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1A}\frac{{\mathrm{di}}_{1A}}{\mathrm{dt}})-n_T(u_{2A}+{\mathrm{<figure-callout\; id="2A"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{2A}{i}_{2A}+{\mathrm{<figure-callout\; id="2A"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{2A}\frac{{\mathrm{di}}_{2A}}{\mathrm{dt}})\\ K_B=(u_{1B}-{\mathrm{<figure-callout\; id="1B"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{1B}{i}_{1B}-{\mathrm{<figure-callout\; id="1B"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1B}\frac{{\mathrm{di}}_{1B}}{\mathrm{dt}})-n_T(u_{2B}+{\mathrm{<figure-callout\; id="2B"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{2B}{i}_{2B}+{\mathrm{<figure-callout\; id="2B"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{2B}\frac{{\mathrm{di}}_{2B}}{\mathrm{dt}})\\ K_C=(u_{1C}-{\mathrm{<figure-callout\; id="1C"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{1C}{i}_{1C}-{\mathrm{<figure-callout\; id="1C"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1C}\frac{{\mathrm{di}}_{1C}}{\mathrm{dt}})-n_T(u_{2C}+{\mathrm{<figure-callout\; id="2C"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{2C}{i}_{2C}+{\mathrm{<figure-callout\; id="2C"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{2C}\frac{{\mathrm{di}}_{2C}}{\mathrm{dt}})\end{array}\right.---\left(4\right)$

Because calculating K _A, K _B, K _CThe time can have winding parameter sum of errors instrument transformer voltage and current measurement error, therefore K under the transformer normal operating condition _A, K _B, K _CAll be not equal to 0.

1. the Adaptive Identification of winding parameter

For the tranformer protection principle based on equivalent equation, winding parameter is vital for it.Because the parameter of different accuracy is different to the imbalance influence of the equivalent equation of normal when operation transformer.Amount of unbalance more little for this protection its sensitivity and reliability also just good more, in order to reduce amount of unbalance, the winding parameter that accuracy is high is absolutely necessary.It is unusual difficulty that but winding parameter is directly measured, and the mutual alignment between size, shape and the winding of its numerical value and winding is relevant.After transformer is subjected to the external fault impact, may cause the distortion of winding, therefore also can change the parameter of winding.In order to access high-precision winding parameter, utilize each side electric current and voltage data of transformer under the normal operating condition, as identification model, adopt the method for Recursive Least-square on-line identification winding parameter to obtain winding parameter with the transformer leakage inductance equation.

According to three-phase double winding model, the equivalent equation (1) in the former secondary voltage of simultaneous loop, (2) can get:

$\left\{\begin{array}{c}(u_{1A}-n_T{u}_{2A})-({\mathrm{<figure-callout\; id="1A"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{1A}{i}_{1A}-{\mathrm{<figure-callout\; id="2A"\; label="n\; T\; r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">n</figure-callout>}}_T{r}_{}{}_{2A}{i}_{2A})={\mathrm{<figure-callout\; id="1A"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1A}\frac{{\mathrm{di}}_{1A}}{\mathrm{dt}}-{\mathrm{<figure-callout\; id="2A"\; label="n\; T\; L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">n</figure-callout>}}_T{L}_{}{}_{2A}\frac{{\mathrm{di}}_{2A}}{\mathrm{dt}}\\ (u_{1B}-n_T{u}_{2B})-({\mathrm{<figure-callout\; id="1B"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{1B}{i}_{1B}-{\mathrm{<figure-callout\; id="2B"\; label="n\; T\; r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">n</figure-callout>}}_T{r}_{}{}_{2B}{i}_{2B})={\mathrm{<figure-callout\; id="1B"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1B}\frac{{\mathrm{di}}_{1B}}{\mathrm{dt}}-{\mathrm{<figure-callout\; id="2B"\; label="n\; T\; L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">n</figure-callout>}}_T{L}_{}{}_{2B}\frac{{\mathrm{di}}_{2B}}{\mathrm{dt}}\\ (u_{1C}-n_T{u}_{2C})-({\mathrm{<figure-callout\; id="1C"\; label="r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">r</figure-callout>}}_{1C}{i}_{1C}-{\mathrm{<figure-callout\; id="2C"\; label="n\; T\; r"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">n</figure-callout>}}_T{r}_{}{}_{2C}{i}_{2C})={\mathrm{<figure-callout\; id="1C"\; label="L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1C}\frac{{\mathrm{di}}_{1C}}{\mathrm{dt}}-{\mathrm{<figure-callout\; id="2C"\; label="n\; T\; L"\; filenames="HDA0000025185960000021.png"\; state="\{\{state\}\}">n</figure-callout>}}_T{L}_{}{}_{2C}\frac{{\mathrm{di}}_{2C}}{\mathrm{dt}}\end{array}\right.---\left(5\right)$

Because Transformer Winding resistance can directly record, and when Transformer Winding electric current and voltage information is gathered in real time, the left side of above equation is known, and the right is because leakage inductance the unknown, therefore can utilize least square method to carry out the winding parameter identification, thereby obtain each mutually former secondary winding leakage inductance value.

In the formula (5), r _1j, r _2j, L _1j, L _2jBe the intrinsic parameter of Transformer Winding, wherein winding resistance r _1j, r _2jRelevant with line footpath, the number of turn and material, can directly measure; And L _1j, L _2jRelevant with size, shape and the arrangement of winding, its value is difficult to directly measure and change along with winding deformation.Therefore accurately obtain the winding leakage inductance parameter, not only can improve protection sensitivity, also be based on the basis of the winding deformation on-line monitoring realization of leakage inductance parameter variable quantity simultaneously.With equation (5) is model, and the electric current and voltage data when utilizing transformer normally to move take the real-time accurate Calculation leakage inductance parameter of parameter identification algorithm to become the bridge of tranformer protection and the integrated realization of winding deformation on-line monitoring.With equation (5) is identification model, selects for use least-squares algorithm to realize the on-line identification of winding leakage inductance parameter.Least square method be a kind of be criterion to select error sum of squares for use, the mathematical method that the optimized parameter that comes best fit to go out to meet experimental data is estimated.In the formula (5), L _1j, L _2jBe the intrinsic parameter of Transformer Winding, for equation (5), order:

$\left\{\begin{array}{c}{g}_1=L_1\\ g_2=L_2\\ y\left(j\right)=u_1\left(k\right)-n_T{u}_2\left(k\right)-r_1{i}_1\left(k\right)+n_T{r}_2{i}_2\left(k\right)\\ x_1\left(j\right)=\frac{i_1(k+1)-i_1(k-1)}{2\mathrm{\&Delta;T}}\\ x_2\left(j\right)=-n_T\frac{i_2(k+1)-i_2(k-1)}{2\mathrm{\&Delta;T}}\end{array}\right.---\left(6\right)$

Leakage inductance parameter then to be identified is:

$\left[\begin{array}{c}{g}_1\\ g_2\end{array}\right]={\left[\begin{array}{cc}{a}_{11}& a_{12}\\ a_{21}& a_{22}\end{array}\right]}^{-1}\left[\begin{array}{c}{b}_1\\ b_2\end{array}\right]---\left(7\right)$

Wherein: $\left\{\begin{array}{c}{b}_i=\underset{k=1}{\overset{m}{\mathrm{\&Sigma;}}}y\left(k\right)g_i\left(k\right)\\ a_{\mathrm{ij}}=\underset{k=1}{\overset{m}{\mathrm{\&Sigma;}}}{g}_i\left(k\right)g_j\left(k\right)\end{array}\right.---\left(8\right)$

Get m continuous sampling point and find the solution above equation group, just can obtain the L under the least square meaning _1k, L _2kEstimates of parameters.

2. the self adaptation of threshold value is adjusted

Can see according to above equivalent equation protection philosophy summary, in theory, work as K _Op≠ 0 can be judged to be the protection zone internal fault.But because the existence of winding parameter error and measurement error of transformer, make formula (4) under normal operating condition and be a non-vanishing value K under the external short circuit state _UbIf the winding parameter error is respectively δ r _1j, δ r _2j, δ L _1j, δ L _2jThe voltage and current measurement error of being introduced by instrument transformer is δ u _1j, δ u _2j, δ i _1j, δ i _2jThen under the transformer normal operating condition, amount of unbalance K _UbCan be expressed as:

$K_{\mathrm{ub}}\left(t\right)=(\mathrm{\&delta;}{u}_{1j}-n_T\mathrm{\&delta;}{u}_{2j})-[(\mathrm{\&delta;}{r}_{1j}{i}_{1j}+\mathrm{\&delta;}{L}_{1j}\frac{{\mathrm{di}}_{1j}}{\mathrm{dt}})-n_T(\mathrm{\&delta;}{r}_{2j}{i}_{2j}+\mathrm{\&delta;}{L}_{2j}\frac{{\mathrm{di}}_{2j}}{\mathrm{dt}})]-\left[(r_{1j}\mathrm{\&delta;}{i}_{1j}+L_{1j}\frac{\mathrm{d\&delta;}{i}_{1j}}{\mathrm{dt}})\right]$

$-n_T(r_{2j}\mathrm{\&delta;}{i}_{2j}+L_{2j}\frac{\mathrm{d\&delta;}{i}_{2j}}{\mathrm{dt}})]-[(\mathrm{\&delta;}{r}_{1j}\mathrm{\&delta;}{i}_{1j}+\mathrm{\&delta;}{L}_{1j}\frac{\mathrm{d\&delta;}{i}_{1j}}{\mathrm{dt}})-n_T(\mathrm{\&delta;}{r}_{2j}\mathrm{\&delta;}{i}_{2j}+\mathrm{\&delta;}{L}_{2j}\frac{d{\mathrm{\&delta;i}}_{2j}}{\mathrm{dt}})]---\left(9\right)$

$={\mathrm{\&epsiv;}}_u\left(t\right)+{\mathrm{\&epsiv;}}_i\left(t\right)$

By formula (9) as can be seen, K _Ub(t) form by two: first ε _u(t) expression is because the amount of unbalance that voltage transformer error causes; Second ε _i(t) comprised the amount of unbalance that brings owing to parameter error summation current transformer error two parts, the error of winding parameter is a definite value, therefore the amount of unbalance ε that is brought by this two parts error _i(t) value all is directly proportional with the electric current that flows through winding.

Equivalent equation under the frequency domain is to obtain by the Fourier transform to equation under the time domain, for uneven quantitative analysis, formula (9) is carried out Fourier transform, obtains amount of unbalance K under the frequency domain _{ω ub}:

$K_{\mathrm{\&omega;ub}}=(\mathrm{\&delta;}{\stackrel{\&CenterDot;}{U}}_{1j}-n_T\mathrm{\&delta;}{\stackrel{\&CenterDot;}{U}}_{2j})-\left[(\mathrm{\&delta;}{r}_{1j}{\stackrel{\&CenterDot;}{I}}_{1j}+\mathrm{j\&omega;\&delta;}{L}_{1j}{\stackrel{\&CenterDot;}{I}}_{1j})\right]-n_T(\mathrm{\&delta;}{r}_{2j}{\stackrel{\&CenterDot;}{I}}_{2j}+\mathrm{j\&omega;\&delta;}{L}_{2j}{\stackrel{\&CenterDot;}{I}}_{2j})$

$-[(r_{1j}\mathrm{\&delta;}{\stackrel{\&CenterDot;}{I}}_{1j}+\mathrm{j\&omega;}{L}_{1j}\mathrm{\&delta;}{\stackrel{\&CenterDot;}{I}}_{1j})-n_T(r_{2j}\mathrm{\&delta;}{\stackrel{\&CenterDot;}{I}}_{2j}+\mathrm{j\&omega;}{L}_{2j}\mathrm{\&delta;}{\stackrel{\&CenterDot;}{I}}_{2j})]-[\left(\mathrm{\&delta;}{r}_{1j}\mathrm{\&delta;}{\stackrel{\&CenterDot;}{I}}_{1j}\right)$ (10)

$+\mathrm{j\&omega;\&delta;}{L}_{1j}\mathrm{\&delta;}{\stackrel{\&CenterDot;}{I}}_{1j})-n_T(\mathrm{\&delta;}{r}_{2j}\mathrm{\&delta;}{\stackrel{\&CenterDot;}{I}}_{2j}+\mathrm{j\&omega;\&delta;}{L}_{2j}\mathrm{\&delta;}{\stackrel{\&CenterDot;}{I}}_{2j})]$

$={\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}_{\mathrm{\&omega;u}}+{\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}_{\mathrm{\&omega;i}}$

As can be seen from the above equation, this amount of unbalance also is made up of two parts:

It is the amount of unbalance that causes by voltage transformer error;

It is the amount of unbalance that causes by current transformer error and winding parameter error.When transformer normally moves, only contain fundamental component in the circuit, so the electric current and voltage in this formula all is the effective value of first-harmonic.

According to above analysis as can be seen, no matter be amount of unbalance K under the time domain _UbOr the amount of unbalance K under the frequency domain _{ω ub}, the size of its value all with equation (9), (10) in winding parameter r _1j, r _2j, L _1j, L _2jClose relation.

(1) quick-action unit

" quick-action " of protection is the basic demand of protective relaying device, and its purpose is the time of minimizing system at big electric current, subnormal voltage operation, reduces the damaged condition of equipment, improves the stability of system.For transformer, when serious troubles inside the sample space takes place, especially need to excise fast fault.

Therefore, the effect of quick-action unit is exactly when catastrophe failure takes place in the transformer district, can accomplish to excise at a high speed fault.But, consider under the outward catastrophe failure situation of generating region and protect not malfunction, so its threshold value is:

K _thj(t)＝k _max(|K _ubj(t)|+2|ε _umax(t)|) (11)

In the formula:

k _MaxFlow through when the most serious external area error taking place for transformer the electric current I of transformer ' ₁Electric current I when normally moving with transformer ₁Ratio;

S ε _UmaxIt is the absolute value sum of voltage transformer worst error in the cycle.

And interior K ' of cycle after the fault _jAbsolute value sum SK ' _jBe the actuating quantity ∑ K of protection _Op, that is:

∑K _opj＝SK′ _j (12)

By the size of comparison amount and braking amount, judge whether generating region internal fault of transformer, therefore obtain tranformer protection criterion definition based on the equivalent equation principle of full dose:

∑K _opj＞K _relSK _thj (13)

Or ∑ K _Opj/ k _Rel1SK _Thj＞1 (14)

In the formula: k _Rel1For the protection safety factor, generally get 1.5.

Because its protection braking amount is set before protection starts and is finished, so work as K _OpWhen pointwise adds up in case satisfy protection criterion (7) or (8), then protection action immediately, so operate time of protection can be greater than a cycle, and the serious more responsiveness of internal fault is fast more.In addition, because tranformer protection is to differentiate a phase equation fault directly to excise three-phase, therefore above criterion is applicable to any phase in the three-phase two winding transformer.

(3) idle-loaded switching-on unit

When no-load transformer closes a floodgate; because the fault-free component exists; therefore when no-load transformer closes in weak fault (for example turn-to-turn fault of small turn number), can't application and trouble component protection element, this just makes protects the sensitivity deficiency when no-load transformer closes in weak turn-to-turn fault.In order to overcome the difficulty that this situation is brought, this protection scheme designs this idle-loaded switching-on protection component and improves sensitivity when protecting idle-loaded switching-on, and its protection threshold value is:

Can get carrying out Fourier transform based on the tranformer protection criterion of the equivalent equation of full dose, based on the protection criterion of full dose, i.e. braking amount is under the frequency domain:

${\mathrm{SK}}_{\mathrm{\&omega;thj}}=k_{\mathrm{\&omega;}}({\mathrm{SK}}_{\mathrm{\&omega;j}}+2S{\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}_{u\max })---\left(15\right)$

In the formula:

K flows through the electric current of transformer when being transformer generating region internal fault

Electric current when normally moving with transformer

Ratio, promptly

S ε _UmaxIt is the absolute value sum of voltage transformer worst error in the cycle.

Simultaneously, the actuating quantity of its protection is ∑ K _{ω opj}

Therefore, the tranformer protection criterion based on the equivalent equation of full dose is under the frequency domain:

∑K _ωopj＞k _rel2SK _ωthj (16)

Or ∑ K _{ω opj}/ (k _Rel2K _{ω thj})＞1 (17)

In the formula: k _Rel2For the protection safety factor, generally get 1.5.

(3) fault component unit

Because quick-action element is to protect not malfunction to determine braking amount K under the catastrophe failure situation of generating region outward _Th(t) if, guarantee reliability and the quick-action protected with sacrificing protection sensitivity, have the problem of tripping in the transformer generating region during fault, therefore, design error failure component unit cooperates with it, remedies the deficiency of sensitivity aspect.

For weak fault in the district, because the less influence to transformer and system of fault current is less, therefore, and the quick-action of the protection of comparing, the sensitivity of protection should be gived top priority.At this moment, the protection threshold value of fault component unit is:

When (k-1) (| K _j(t) |+| ε _Umax(t) |) 〉=| ε _Umax(t) | the time

SK _thj＝(k-1)(SK _j?+ε _umax) (18)

When (k-1) (| K _Ub(t) |+| δ _Umax(t) |)＜| ε _Umax(t) | the time

ΔSK _th(t)＝ε _umax(t) (19)

More than k-1 in two formulas be the fault current multiple, promptly

Δ I _1j, Δ I _2jBe the former secondary fault component of three-phase two winding transformer electric current.

Simultaneously, the actuating quantity of its protection is ∑ Δ K _Opj

Therefore, the protection criterion is:

∑ Δ K _Opj＞k _Rel3S Δ K _ThjOr ∑ Δ K _Opj/ (k _Rel3S Δ K _Thj)＞1 (20)

In the formula: k _Rel3For the protection safety factor, generally get 1.5.

3. the protection criterion is adaptively selected

The analysis of adjusting according to the self adaptation of above Adaptive Identification, threshold value to winding parameter, as can be seen, four elementary cells among the present invention: quick-action unit, fault component unit, idle-loaded switching-on unit and parameter identification and the threshold value unit of adjusting, self all has outstanding advantage, can well finish set task in one aspect, but also have certain defective and problem simultaneously.Use all can not be satisfied relaying protection fully to " four property "---the requirement of reliability, selectivity, sensitivity, quick-action separately.Therefore; the present invention proposes to protect the adaptively selected of criterion on this basis, and its basic goal is exactly by the complete workflow of a cover, effectively makes up above four elementary cells; realize enhancing and complementation on the function, satisfy the requirement of relaying protection " four property ".

As shown in Figure 4, the adaptively selected of protection criterion is described:

1. when external area error takes place, transformer voltage current information typing quick-action criterion, because the quick-action unit is according to the braking amount of adjusting of catastrophe failure outside the protection zone, so reliably be failure to actuate in the quick-action unit; Same, the same differentiation in fault component unit and idle-loaded switching-on unit is external area error, action message;

2. when the generating region internal fault, for non-weak fault, the quick-action criterion at first starts, and trip signal is sent in identification rapidly, the excision fault;

3. for the weak fault of part, the quick-action unit is because the tripping situation then takes place in the sensitivity deficiency.At this moment, protection enters one and judges flow process, and whether stream has electric current by measuring transformer secondary side, judges whether transformer is in the state of idle-loaded switching-on;

4. if the non-unloaded "on" position of transformer this moment then by fault component protection criterion, is discerned weak fault in distinguishing, send trip signal, the excision fault;

5. if transformer is the idle-loaded switching-on state at this moment,, weak fault in distinguishing is discerned, sent trip signal, the excision fault then by idle-loaded switching-on protection criterion.

By above concrete narration as can be seen, no matter be in the transformer district, serious, minor failure in external area error or its district, the present invention can both be by selecting reliable, the sensitive quick identification fault of optimal protection criterion.By protecting the adaptively selected of criterion, accomplish the mutual supplement with each other's advantages of each protected location, satisfy the requirement of relaying protection to " four property ".

4. concrete implementation step

As shown in Figure 1, for implementing the flow chart based on the transformer self-adaptive protection scheme of equivalent equation, concrete steps are as follows:

1. protective device is set the nameplate parameter of protected transformer: short-circuit voltage u after electrifying startup _k%, short circuit loss p _k%, transformer rated capacity S _b, transformer rated voltage U _b, rated current I _b, transformer nominal transformation ratio n _BAccording to nameplate calculation of parameter transformer substitutional resistance r _kWith leakage inductance L _k

2. gather the former limit of transformer three-phase winding voltage current data u in real time _1A, u _1B, u _1C, i _1A, i _1B, i _1C, secondary three-phase winding voltage current data u _2A, u _2B, u _2C, i _2A, i _2B, i _2C, judge according to each side current data sudden change amount of transformer whether protection component starts;

3. protection utilizes catastrophe failure in the transformer quick-action protection component quick identification tranformer protection district after starting, and operate time of protection increases with the fault order of severity and reduces; If the action of quick-action protection component, tripping operation excision fault, package unit involution simultaneously; When quick-action element does not move, judge that by transformer secondary winding current amplitude before differentiating the protection startup transformer is in idle-loaded switching-on state or load operation conditions;

4. if this moment, transformer was in the idle-loaded switching-on state, then protection adopts the frequency domain protection component to judge whether troubles inside the sample space of transformer, if then trip signal excision fault is sent in protection, 2. the package unit involution then returns step if not simultaneously;

5. if transformer is in load operation conditions, then protection adopts the fault component protection component to judge whether troubles inside the sample space of transformer, if then trip signal excision fault, package unit involution are simultaneously sent in protection; Then do not show generation tranformer protection external area error if be judged as troubles inside the sample space; this time zone outwash is hit electric current and may the winding of transformer be exerted an influence; therefore enter parameter identification more new element protection parameter and action protection threshold value are carried out real-time update, return step and 2. gather next each side electric current and voltage information of transformer constantly again.

The result obtains according to the dynamic model experiment data verification; as shown in table 1; this adaptive guard scheme is not influenced by magnetizing inrush current; for the tranformer protection scheme of various states all can the right area subregion inside and outside fault, can be for the transformer quick-action protection that serious troubles inside the sample space takes place, and fault is serious more fast with its excision; responsiveness is fast more; when in the transformer generating region during weak fault, protection still can have higher sensitivity with its excision in the time of a cycle.

Table 1

Above content is to further describing that the present invention did in conjunction with concrete preferred implementation; can not assert that the specific embodiment of the present invention only limits to this; for the general technical staff of the technical field of the invention; without departing from the inventive concept of the premise; can also make some simple deduction or replace, all should be considered as belonging to the present invention and determine scope of patent protection by claims of being submitted to.

Claims (7)

1. transformer self-adaptive protector is characterized in that: this device comprises quick-action unit, fault component unit, idle-loaded switching-on unit, parameter identification and the threshold value unit of adjusting.

2. a kind of guard method of transformer self-adaptive protector according to claim 1 is characterized in that, according to following steps:

1. protective device is set the nameplate parameter of protected transformer: short-circuit voltage u after electrifying startup _k%, short circuit loss p _k%, transformer rated capacity S _b, transformer rated voltage U _b, rated current I _b, transformer nominal transformation ratio n _B

2. gather the former limit of transformer three-phase winding voltage current data u in real time _1j, i _1j, j is A, B, C three-phase, secondary three-phase winding voltage current data u _2j, i _2j, judge according to each side current data sudden change amount of transformer whether protection component starts;

3. protection utilizes catastrophe failure in the transformer quick-action protection component quick identification tranformer protection district after starting, and operate time of protection increases with the fault order of severity and reduces; If the action of quick-action protection component, tripping operation excision fault, package unit involution simultaneously; When quick-action element does not move, judge that by transformer secondary winding current amplitude before differentiating the protection startup transformer is in idle-loaded switching-on state or load operation conditions;

4. if this moment, transformer was in the idle-loaded switching-on state, then protection adopts the frequency domain protection component to judge whether troubles inside the sample space of transformer, if then trip signal excision fault is sent in protection, 2. the package unit involution then returns step if not simultaneously;

5. if transformer is in load operation conditions, then protection adopts the fault component protection component to judge whether transformer distinguishes interior weak fault, if then trip signal excision fault, package unit involution are simultaneously sent in protection; If not enter parameter identification more new element protection parameter and action protection threshold value are carried out real-time update, return step and 2. gather next each side electric current and voltage information of transformer constantly again.

3. as the guard method of a kind of transformer self-adaptive protector as described in the claim 2, it is characterized in that: adopt based on equivalent equation tranformer protection principle,

For the three-phase two winding transformer, former limit winding voltage equation is:

The equivalent equation in secondary voltage loop is

In the formula, u _1j, u _2jBe each phase winding phase voltage of former secondary, i _1j, i _2jBe each phase winding phase current of former secondary, ψ _MjBe the magnetic linkage of winding linkage, r _1j, r _2jAnd L _1j, L _2jBe former secondary each phase winding resistance and leakage inductance; Utilize the former and deputy polygonal voltage loop equation of transformer (1), (2), cancellation mutual inductance magnetic linkage, thus only comprised the equivalent equation (3) of former and deputy polygonal voltage and electric current:

Whether the up-to-date style that breaks down in the tranformer protection district (3) is no longer set up, therefore become Rob Roy to judge whether to break down in the tranformer protection district by discriminant (3).

4. as the guard method of a kind of transformer self-adaptive protector as described in the claim 2, it is characterized in that on-line parameter identification and threshold value self adaptation adjust, performing step is:

In the formula (3), winding leakage inductance parameter L _1j, L _2jCan't directly measure, utilize the normal working voltage current data of transformer according to formula (3) to winding leakage inductance parameter L _1j, L _2jCarrying out on-line identification obtains;

Because there are error in instrument transformer voltage, current measurement, there are deviation in winding resistance and leakage inductance parameter value simultaneously, so normal operating condition following formula (3) equal sign right side is to be not equal to zero value to be designated as K _Ubj, the instantaneous worst error of voltage transformer is ε _Ujmax

The protection threshold value of adaptive setting comprises SK _UbjWith S ε _Ujmax, SK wherein _UbjK during for normal operation _UbjOne cycle absolute value sum, S ε _UjmaxVoltage transformer worst error one cycle absolute value sum is according to voltage transformer maximum relative error δ _1jmax, δ _2jmaxCalculate, promptly

。

5. as the guard method of a kind of transformer self-adaptive protector as described in the claim 2, the quick-action unit is used for excising catastrophe failure in the tranformer protection district fast, it is characterized in that the outer catastrophe failure protection in district is failure to actuate, promptly

SK _opj＞k _relk _max(SK _ubj+2Sε _ujmax) (5)，

Wherein protect actuating quantity SK _OpjBe the pointwise addition of protection startup back formula (3) right-hand side expression, promptly

k _MaxFor short-circuit current multiple during bus three-phase metallic short circuit fault outside the tranformer protection district, be k according to transformer nameplate calculation of parameter _Max=1/u _k%;

k _Rel1For the protection safety factor, get 1.5.

6. as the guard method of a kind of transformer self-adaptive protector as described in the claim 2, fault was reliably differentiated when the idle-loaded switching-on unit was used for no-load transformer and closes a floodgate, and adopted equivalent equation principle frequency domain criterion, it is characterized in that:

SK _ωopj＞k _rel2k ₁(SK _ubj+2Sε _ujmax) (6)，

SK in the formula (6) _{ω opj}, SK _Ubj, S ε _UjmaxBe frequency domain value;

k ₁Flow through the electric current of transformer during for transformer generating region internal fault Electric current when normally moving with transformer

Ratio, promptly

k _Rel2For the protection safety factor, get 1.5.

7. as the guard method of a kind of transformer self-adaptive protector as described in the claim 2, the fault component unit is used in the load transformer Operational Zone it is characterized in that if the sensitivity of fault is differentiated:

SΔK _opj＞k _rel3SK _th

In the formula

SK _ThSetting principle is

As (k-1) (SK _Ub+ S ε _Umax) 〉=S ε _UmaxThe time, SK _Th=(k-1) (SK _Ub+ S ε _Umax)

As (k-1) (SK _Ub+ S ε _Umax)＜S ε _UmaxThe time, SK _Th=S ε _Umax

Wherein

Δ I _1j, Δ I _2jBe the former secondary fault component of three-phase two winding transformer electric current;

k _Rel3For the protection safety factor, generally get 1.5.

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