CN1441257A - In-situ fault diagnosing technology for turn-to-turn short-circuit of transformer windings based on change in loss - Google Patents

Abstract

The present invention relates to in-situ fault diagnosing technology for turn-to-turn short circuit of transformer windings based on change in loss. The technological scheme includes sampling and measuring the voltage and currents of transformer in both sides, calculating the power in both sides, calculating the power difference in both sides or loss of the transformer, comparing with historical data of the transformer to determine whether to exhibit turn-to-turn short circuit fault and the fault degree. The present invention makes it possible to find the turn-to-turn short circuit fault early and accurately and determine the phase the fault is in while monitoring the current, voltage, active power, reactive power, power factor, etc.

Description

Transformer Winding turn-to-turn short circuit on-line fault diagnosis technology based on the loss variation

Technical field

What the present invention relates to is a kind of Winding in Power Transformer turn-to-turn short circuit on-line fault diagnosis technology based on the loss variation tendency, belongs to the electrical reliability technical field.

Background technology

Power transformer is the major equipment in the power transmission and transformation system, is the nucleus equipment at power transmission and transformation station.The quality of power transformer running status will be directly connected to the reliability of whole electric system.Though the operational reliability level of power transformer has raising in recent years, does not satisfy the requirement of electric system far away, the fault of power transformer happens occasionally.Statistical data shows that turn-to-turn short circuit is one of modal fault of power transformer.Cause the reason of turn-to-turn short circuit a lot: technology is coarse when making as coil, makes insulation be subjected to mechanical damage; High temperature makes insulation ag(e)ing; Under electrodynamic action, make wire turn generation axial displacement, the wearing and tearing or the like of will insulating.At present, to interturn short-circuit failure diagnosing gas chromatographic analysis more effectively (DGA), it is analyzed the transformer running status according to the chromatogram of dissolved gases in the transformer oil, finds the inherent vice of transformer early, and its technology is comparative maturity comparatively speaking.But it is mainly used in qualitative analysis, have three significantly not enough: the one, can not the location determination fault; The 2nd, reaction is slow, the cycle is long; Thirdly be that it is difficult for capturing sudden failure symptom etc.

Summary of the invention

The objective of the invention is to defective at above-mentioned existence, propose a kind of initial failure that can diagnose out the transformer turn-to-turn short circuit apace, the step of going forward side by side is carried out the Winding in Power Transformer turn-to-turn short circuit on-line fault diagnosis technology of localization of fault (promptly analyzing the fault winding in which phase).The technology of the present invention scheme of determining: voltage, the electric current of each side of sampled measurements transformer, power according to each side of sampled value calculating transformer, calculating each side power difference again is the loss of transformer, compare with the historical data of transformer loss, according to the variation tendency of its loss, diagnose out Transformer Winding to have or not the degree of shorted-turn fault and fault.Active loss under the transformer unfaulty conditions is according to the on-the-spot virtual condition decision of transformer, before putting into operation, system should confirm that transformer does not have fault, at this moment, measuring transformer is at electric current, the voltage (mainly being the value in the range of operation of voltage and current in actual capabilities) of its each each side of phase under the various running statuses, the loss of calculating transformer, simulate the damage curve under the normal condition of this transformer according to this loss, i.e. the relation curve of the loss of transformer and its electric current, voltage.

Calculate the power of every each side of phase by the sampled measurement of transformer, further calculate the loss increment of each phase, according to the difference of three-phase loss increment Changing Pattern, the be out of order phase at winding place of diagnosis.

Advantage of the present invention: can diagnose out the slight shorted-turn fault of power transformer early; Can carry out the phasing of fault, promptly judge fault and occur in which phase winding; But inline diagnosis; System architecture is simple, and engineering construction is convenient, need not transformer itself is done any change; And also have the electric current, voltage of other multiple subsidiary function such as real-time each side of monitoring transformer, meritorious, idle, power factor etc.

Appended drawings is that Yd connects three-phase transformer fault diagnosis system synoptic diagram

A among the figure, B, C and a, b, c are former side and secondary side, and X, Y, Z and x, y, z are the ends of former side's terminal and pair side.

Embodiment

The form of power transformer has a variety of, but this diagnosis theory based on the loss variation tendency is the same, below with Yd connect the three-phase transformer fault diagnosis system be the example Benq in the embodiment of the Winding in Power Transformer interturn short-circuit failure diagnosing technology of loss variation tendency.

The contrast accompanying drawing

The double winding three-phase transformer that Yd connects, the temperature (generally being the transformer oil temperature) of electric current, voltage and the transformer of each each side of phase of sampling with high precision measurement is totally 13 amounts, promptly

 _AB _BC _CA

 _ab _bc _ca

t

(to Y _N, the three-phase transformer that d connects, the zero line voltage and current of also will sampling).

General power P by these former pair sides of Parameters Calculation transformer ₁, P ₂, its difference is the total losses ~ P of transformer.

After system puts into operation, the relation curve of the loss of earlier automatic match transformer unfaulty conditions and electric current, voltage.The active loss of transformer under unfaulty conditions determines according to on-the-spot transformer virtual condition, before putting into operation, system should confirm that transformer does not have fault, at this moment, electric current, the voltage of measuring transformer its each each side of phase under various possibility running statuses, and the loss of identical computing method calculating transformer when using with fault diagnosis, relation according to this loss and electric current, voltage, by existing automatic fitting technique, the loss variation rule curve when simulating this transformer non-fault under various load conditions (value when amounting to into standard temperature).It is the relation curve of the loss of transformer and electric current, voltage.

Whatsoever the transformer of connecting mode when shorted-turn fault takes place, the short circuit circulation of a closure will occur.Because every circle electromotive force of large-scale power transformer is higher, and its short-circuit impedance is very little, circulation very big (but from the transformer outside terminal, its electric current does not often have obvious variation).This circulation causes heating, though every circle resistance of transformer is very little, because square being directly proportional of its heating and electric current, i.e. Q ∝ I ²γ, so the transformer heating that this circulation causes is also not really little, this makes the loss of transformer increase.

After system formally puts into operation, voltage, the electric current of each side of sampled measurements transformer, difference power according to each side of sampled value calculating transformer, it is the loss of transformer, the historical data of this loss and transformer loss relatively (is measured the temperature of winding temperature or transformer oil according to field condition, and is converted).According to the variation tendency of transformer loss,, then diagnose Transformer Winding that the degree of shorted-turn fault and fault is arranged if the variation tendency of transformer loss is unusual.The phasing diagnosis

So-called phasing diagnosis is exactly to diagnosing the transformer that turn-to-turn short circuit has taken place further to determine the phase at fault winding place.

To three-phase transformer, to disregard under the situation of leakage flux, the power on the same iron core column of transformer is in a basic balance, total electric power that the gross electric capacity of importing on the promptly same iron core column should equal to export adds the various losses of this phase.So if the winding generation turn-to-turn short circuit of a certain phase of transformer, then the loss of this phase will increase, and the loss of two-phase is constant substantially in addition.So, sampled measurement by the phase-splitting technology, is calculated the power of every each side of phase, and further calculate the loss increment of each phase, according to the difference of three-phase loss increment Changing Pattern, diagnose the phase at the winding place of being out of order.

We generally are the phase currents that can't directly measure the transformer triangle winding in engineering is used, and must carry out phase-splitting and handle.The key that phase-splitting is handled is asked phase current by line current in the winding that triangle connects.

Native system adopts symmetrical component method to ask the forward-order current and the negative-sequence current of delta windings earlier.When transformer is inner asymmetric, according to the line current that measures

Decompose and obtain forward-order current:

, negative-sequence current:

Asymmetric three-phase transformer is regarded as the three-phase transformer of two symmetries, and, try to achieve the phase current positive-negative sequence component of these two transformers according to the phase current of symmetrical three-phase transformer and the relation of line current

With

When containing Y _NDuring winding, also to consider the circulation influence in the delta windings.Though delta windings can not have the electric current that flows out or flow to whole winding, promptly the three-phase current sum is zero.But to Y _N, the transformer that d connects can have circulation in its delta windings

, its size is tried to achieve by the transformer voltage ratio relation by the zero-sequence current in the Y winding, that is: Y _N, the circulation of the transformer intermediate cam shape side winding that d connects is ${\stackrel{\·}{I}}_{\mathrm{phl}}={\stackrel{\·}{I}}_{a0}=k{\stackrel{\·}{I}}_{A0}$

The no-load voltage ratio of k in the formula---transformer,

---the circulation of transformation low-pressure side, establishing low-pressure side here is that triangle connects;

---the zero-sequence current of transformer high-voltage side, can directly measure or calculate by the triple-phase line current summation.Here establishing the star side is the high-pressure side.

Each preface current summation of each phase of triangle side is obtained total phase current.As ${\stackrel{\·}{I}}_{\mathrm{ax}}={\stackrel{\·}{I}}_{\mathrm{ax}+}+{\stackrel{\·}{I}}_{\mathrm{ax}-}+{\stackrel{\·}{I}}_{\mathrm{ax}\left(\right)}$

At last, the difference power (loss) of the phase winding on the iron core column of seeking common ground, and with the historical data of transformer loss relatively, according to the difference of three-phase loss increment Changing Pattern, the be out of order phase at winding place of diagnosis.

Claims (2)

1, Transformer Winding turn-to-turn short circuit on-line fault diagnosis technology based on the loss variation, the voltage that it is characterized in that each side of sampled measurements transformer, electric current, power according to each side of sampled value calculating transformer, calculating each side power difference again is the loss of transformer, compare with the historical data of transformer loss, variation tendency according to its loss, diagnose out Transformer Winding to have or not the degree of shorted-turn fault and fault, active loss under the transformer unfaulty conditions is according to the on-the-spot virtual condition decision of transformer, before putting into operation, system should confirm that transformer does not have fault, at this moment, the electric current of measuring transformer its each each side of phase under various running statuses, voltage, the loss of calculating transformer, simulate the damage curve under the normal condition of this transformer according to this loss, i.e. the loss of transformer and its electric current, the relation curve of voltage.

2, the Transformer Winding turn-to-turn short circuit on-line fault diagnosis technology that changes based on loss as claimed in claim 1, it is characterized in that power according to each side of sampled value calculating transformer, can calculate the power of every each side of phase by sampled measurement, further calculate the loss increment of each phase, according to the difference of three-phase loss increment Changing Pattern, diagnose the phase at the winding place of being out of order.