CN101599635B - Method for enhancing differential protection performance by coordination of mutation quantity fault discrimination and fuzzy harmonic analysis - Google Patents

Abstract

The invention relates to a method for enhancing differential protection performance by the coordination of mutation quantity fault discrimination and fuzzy harmonic analysis, which utilizes different characteristics of difference current and braking current mutation quantity to distinguish the internal and external faults of an area under different fault conditions. After a fault type is distinguished by the discrimination method, a fuzzy harmonic analysis criterion is combined to enhance the accuracy of fault discrimination so as to enhance the reliability and sensitivity of differential protection. The method is already adopted in a complete set of protection device of a DSA serial transformer and both the simulation results and the site practical situation indicate that the method has good prevention effect on reasons which easily cause differential misoperation, such as TA saturation, sympathetic surge, AD abnormity, and the like.

Description

Mutation quantity fault discrimination mating die fuzzy harmonic analysis improves the method for differential protection performance

Technical field

The present invention relates to a kind of new method of utilizing the novel fault diagnostic method comprehensively to improve the differential protection reliability in conjunction with the harmonic analysis criterion.

Background technology

China's tranformer protection has all adopted microcomputer type transformer differential protection device basically at present; but the precision maneuver rate of protection is generally not high; according to present interrelated data statistics; the performance factor of transformer differential protection has only about 75% at present, far can not reach the needs of site safety operation.Cause at present the main cause of biased differential protection misoperation comprise following some

1. the outer TA in district is saturated, executes although each company's product all has saturated the retouching of anti-TA, still might cause protecting malfunction in the TA saturation history, protects tripping or deferred action when perhaps TA breaks down conversion after saturated.

2. and echo surge current, now and the research of echo surge current also progressively deeply, but generation is also arranged by chance with differential misoperation that echo surge current causes.

3. inner AD fault, repeatedly on-the-spot record ripple are found, when the inner AD of protection breaks down, because the existence of part " bad point " causes differential misoperation.

Summary of the invention

Technical problem to be solved by this invention is; overcome existing deficiency; provide a kind of mutation quantity fault discrimination mating die fuzzy harmonic analysis to improve the method for differential protection performance, facts have proved that reliability and the sensitivity to differential protection is enhanced, have excellent application value.。

The technical solution adopted for the present invention to solve the technical problems is as follows: mutation quantity fault discrimination mating die fuzzy harmonic analysis improves the method for differential protection performance, and concrete steps are as follows:

(1), utilizes inequality (I) brake monitoring jump-value of current Δ I _ResWhether open constant K greater than criterion _Set1If inequality (I) is set up, and then goes to step (2); Otherwise repeat this step;

ΔI _res＞K _set1 (I)

In the formula, the open constant K of criterion _Set1Span be [0.1Ie, 0.3Ie], Ie is the transformer rated current;

(2), judge whether inequality (II) is set up, if inequality (II) establishment illustrates that then fault type belongs to external area error or abnormality, and goes to step (3); Otherwise illustrate that fault type is to belong to troubles inside the sample space, select to reduce the protection time-delay this moment, to accelerate operate time of protection;

ΔI _diff＜K _set2*ΔI _res (II)

In the formula, Δ I _DiffBe spill current sudden change amount, Δ I _ResBe stalling current sudden change amount, K _Set2Be the coefficient of ratio, its span is [1.2,1.4],

(3), utilize formula (III) to calculate respectively 2 times, 3 times, the degree of membership of 5 subharmonic is designated as

And go to step (4);

$m_A\left(\frac{I_n}{I_1}\right)=\left\{\begin{array}{cc}0& \left(\frac{I_n}{I_1}\right)<B_1\\ [{\left(\frac{I_n}{I_1}\right)}^2-{{\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="H2009100302053E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}_1}^2]/(B_2^2-{\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="H2009100302053E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}_1^2)& {\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="H2009100302053E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}_1\&le;\left(\frac{I_n}{I_1}\right)\&le;B_2\\ 1& \left(\frac{I_n}{I_1}\right)>B_2\end{array}\right.---\left(\mathrm{III}\right)$

In the formula, I ₁Be fundamental current amplitude, I _nBe nth harmonic current amplitude, B parameter ₁Span be [7%, 12%], B parameter ₂Span be [25%, 30%];

(4), judge 2 times, 3 times, the comprehensive degree of membership m of 5 subharmonic _A(x) whether satisfy formula (IV), judge if formula (IV) is set up saturated or other abnormal conditions of CT to have occurred this moment, take corresponding safeguard measure, comprise increasing differential protection time-delay, temporary transient Blocking Differential Protection; If formula (IV) is false, Blocking Differential Protection not then,

$m_A\left(x\right)=\frac{1}{2+K_{\mathrm{set}3}}[m_A\left(\frac{I_2}{I_1}\right)+m_A\left(\frac{I_3}{I_1}\right)+K_{\mathrm{set}3}*m_A\left(\frac{I_5}{I_1}\right)]>K_{\mathrm{set}4}---\left(\mathrm{IV}\right)$

In the formula, parameter K _Set3Span be [0.2,0.3], parameter K _Set4Span be [0.3,0.4].In the formula (IV) to 5 subharmonic degrees of membership

Carried out special processing, promptly in 5 subharmonic degrees of membership Basic superior parameter K _Set3, this is because in most of the cases 5 subharmonic content are less, so its weight in comprehensive degree of membership is less.

Beneficial effect of the present invention is as follows: the present invention adopts the sudden change amount as criterion, can guarantee the sensitivity of criterion, the method is external area error or troubles inside the sample space in the time of can differentiating the fault generation accurately, conversion also can in time determine the fault type after the fault conversion even break down, for the fail safe and the sensitivity of differential protection provides good guarantee; Introduce fuzzy algorithmic approach and comprehensively judge each harmonic content, to reduce fixedly definite value the influence of sensitivity and degree of safety.Herein the each harmonic membership function is set at and increases curve surely, increase rapidly in high-load part weight, to improve the sensitivity of this scheme, guarantee reliable Blocking Differential Protection when heavily saturated, and less in low content place weight, to improve the fail safe of this scheme, prevent the mistake latch-up protection; Saturated withdraw from or during situations such as the conversion of breaking down, this moment, each harmonic content can reduce rapidly, thus open and protection does not once more influence the sensitivity of differential protection.This harmonic wave Fuzzy Criteria can determine external area error or other abnormal conditions accurately in conjunction with the spill current fault distinguishing method that is proposed in 1 joint, and latch-up protection in time prevents differential protection malfunction.And when troubles inside the sample space CT is saturated, do not adopt the harmonic wave Fuzzy Criteria can not select latch-up protection; conversion is by the outer saturated troubles inside the sample space that is converted in district even break down; this time-harmonic wave Fuzzy Criteria in time withdraws from; and this moment, harmonic content was often lower; the harmonic wave Fuzzy Criteria can not satisfy barring condition, the sensitivity of action in can guaranteeing to distinguish.

At with background technology in three kinds of reasons that cause the biased differential protection misoperation easily proposing, adopt the inventive method that effect is preferably all arranged:

1, the outer TA saturation problem in district

Utilize fault type differentiation accurately and fuzzy harmonic wave criterion to provide good solution to the TA saturation problem; digital-to-analogue repeatedly, dynamic simulation test is the result show, at the electric current linear transform area during greater than the saturated conditions more than the 1ms; all can realize saturated locking, not malfunction of differential protection.Even, still can guarantee to protect reliable locking because the long-time saturated secondary current that causes is in saturation condition for a long time.The open and protection in time that breaks down again after saturated has guaranteed the reliability of protection action.

2 and the echo surge current problem

When closing the echo surge current generation; belong to passing through property for transformer and shove this moment; mutation quantity fault type criterion can determine and be external area error this moment this moment; and fuzzy harmonic wave criterion can comprehensively adopt 2; 3; 5 subharmonic, thus avoided only adopting 2 times or 3 subharmonic constitute criterion and closing the shortcoming that echo surge current later stage harmonic content can not latch-up protection when reducing, realized the function of accurate Blocking Differential Protection.

3, AD sampling sudden change problem

When occurring indivedual " bad point " in the AD sampled point; just sometimes because external electromagnetic interference or AD sampling A problem cause some points or the unexpected situation that becomes big or diminish of continuous several point value through harmonic analysis; this moment, its each harmonic content was all higher, adopted fuzzy harmonic wave criterion to prevent that the differential protection misoperation effect is better.

The present invention utilizes the principle of mutation quantity fault type identification in conjunction with fuzzy harmonic wave criterion, by to different faults type or analysis of abnormal, introduce mutation quantity fault type identification method, ask for spill current sudden change amount and stalling current sudden change amount respectively, by comparing the difference of its variation tendency, distinguish the fault type after internal fault external fault and fault are changed.On the basis that accurately determines fault type, the harmonic components in the phase current is analyzed, proposed to utilize the fuzzy membership functions method to improve the harmonic analysis method of accuracy.Result of the test and The field prove that this method can effectively improve the fail safe and the sensitivity of differential protection, and implementation method is simple, have very strong engineering using value.

Description of drawings

Fig. 1 is a harmonic wave membership function curve chart.

Fig. 2 improves the method flow diagram of differential protection performance for mutation quantity fault discrimination mating die fuzzy harmonic analysis of the present invention.

Embodiment

With reference to the accompanying drawings and in conjunction with the embodiments the present invention is described in further detail.But the invention is not restricted to given example.

As shown in Figure 2, mutation quantity fault discrimination mating die fuzzy harmonic analysis of the present invention improves the method for differential protection performance, and concrete steps are as follows:

(1), utilizes inequality (I) brake monitoring jump-value of current Δ I _ResWhether open constant K greater than criterion _Set1If inequality (I) is set up, and then goes to step (2); Otherwise repeat this step;

ΔI _res＞K _set1 (I)

In the formula, the open constant K of criterion _Set1Span be [0.1Ie, 0.3Ie], Ie is the transformer rated current;

(2), judge whether inequality (II) is set up, if inequality (II) establishment illustrates that then fault type belongs to external area error or abnormality, and goes to step (3); Otherwise illustrate that fault type is to belong to troubles inside the sample space, select to reduce the protection time-delay this moment, to accelerate operate time of protection;

ΔI _diff＜K _set2*ΔI _res (II)

In the formula, Δ I _DiffBe spill current sudden change amount, Δ I _ResBe stalling current sudden change amount, K _Set2Be the coefficient of ratio, its span is [1.2,1.4],

(3), utilize formula (III) to calculate respectively 2 times, 3 times, the degree of membership of 5 subharmonic is designated as

And go to step (4);

$m_A\left(\frac{I_n}{I_1}\right)=\left\{\begin{array}{cc}0& \left(\frac{I_n}{I_1}\right)<B_1\\ [{\left(\frac{I_n}{I_1}\right)}^2-{{\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="H2009100302053E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}_1}^2]/(B_2^2-{\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="H2009100302053E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}_1^2)& {\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="H2009100302053E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}_1\&le;\left(\frac{I_n}{I_1}\right)\&le;B_2\\ 1& \left(\frac{I_n}{I_1}\right)>B_2\end{array}\right.---\left(\mathrm{III}\right)$

In the formula, I ₁Be fundamental current amplitude, I _nBe nth harmonic current amplitude, B parameter ₁Span be [7%, 12%], B parameter ₂Span be [25%, 30%];

(4), judge 2 times, 3 times, the comprehensive degree of membership m of 5 subharmonic _A(x) whether satisfy formula (IV), judge if formula (IV) is set up saturated or other abnormal conditions of CT to have occurred this moment, take corresponding safeguard measure, comprise increasing differential protection time-delay, temporary transient Blocking Differential Protection; If formula (IV) is false, Blocking Differential Protection not then,

$m_A\left(x\right)=\frac{1}{2+K_{\mathrm{set}3}}[m_A\left(\frac{I_2}{I_1}\right)+m_A\left(\frac{I_3}{I_1}\right)+K_{\mathrm{set}3}*m_A\left(\frac{I_5}{I_1}\right)]>K_{\mathrm{set}4}---\left(\mathrm{IV}\right)$

In the formula, parameter K _Set3Span be [0.2,0.3], parameter K _Set4Span be [0.3,0.4].

Utilize state net DianKeYuan digital-to-analogue laboratory RTDS (Real Time Digital Simulator) to carry out digital-to-analogue emulation.Saturated to TA outside distinguishing in emulation, and echo surge current, the fault conversion has been carried out than detailed simulation analysis etc. situation.In simulation process, adopt the mutation quantity fault type criterion can be in the district when the outer saturated phase current linear transform area of TA is greater than 1ms in conjunction with the DSA8322 protective device of fuzzy harmonic wave criterion, accurately determine fault type and saturated generation, timely Blocking Differential Protection.Outer saturated back is when being converted to troubles inside the sample space in the district, and also timely open and protection of this criterion this moment guarantees to protect the reliability of moving.

Also participate in the dynamic simulation test chamber that utilizes the Central China University of Science and Technology based on the tranformer protection of present principles and carried out dynamic simulation test after digital-to-analogue emulation, a large amount of result of the tests show, this method all has to a great extent raising to differential protection fail safe and sensitivity.

Claims (1)

1. mutation quantity fault discrimination mating die fuzzy harmonic analysis improves the method for differential protection performance, and concrete steps are as follows:

(1), utilizes inequality (I) brake monitoring jump-value of current Δ I _ResWhether open constant K greater than criterion _Set1If inequality (I) is set up, and then goes to step (2); Otherwise repeat this step;

ΔI _res＞K _set1 (I)

In the formula, the open constant K of criterion _Set1Span be [0.1Ie, 0.3Ie], Ie is the transformer rated current;

(2), judge whether inequality (II) is set up, if inequality (II) establishment illustrates that then fault type belongs to external area error or abnormality, and goes to step (3); Otherwise illustrate that fault type is to belong to troubles inside the sample space, select to reduce the protection time-delay this moment, to accelerate operate time of protection;

ΔI _diff＜K _set2*ΔI _res (II)

In the formula, Δ I _DiffBe spill current sudden change amount, Δ I _ResBe stalling current sudden change amount, K _Set2Be the coefficient of ratio, its span is [1.2,1.4],

(3), utilize formula (III) to calculate respectively 2 times, 3 times, the degree of membership of 5 subharmonic is designated as

And go to step (4);

In the formula, I ₁Be fundamental current amplitude, I _nBe nth harmonic current amplitude, B parameter ₁Span be [7%, 12%], B parameter ₂Span be [25%, 30%];

(4), judge 2 times, 3 times, the comprehensive degree of membership m of 5 subharmonic _A(x) whether to satisfy formula (IV), judge if formula (IV) is set up saturated or other abnormal conditions of CT to have occurred this moment, take corresponding protection. measure comprises increasing differential protection time-delay, temporary transient Blocking Differential Protection; If formula (IV) is false, Blocking Differential Protection not then,

In the formula, parameter K _Set3Span be [0.2,0.3], parameter K _Set4Span be [0.3,0.4].

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