SFRA technique for the Transformer winding deformation analysis

IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 09, 2015 | ISSN (online): 2321-0613

SFRA Technique for the Transformer Winding Deformation Analysis Mr. Patil Ritesh Anil1 Prof.A.P.Chaudhari2 Prof. G.K.Mahajan3 1 M.E. Student 2,3Associate Professor 1,2,3 Department of Electrical Engineering 1,2,3 SSGBCOET BhusawalDist: Jalgaon, Maharashtra (India) Abstract— The sweep rate response analysis is widely used technique for identify veiled fault and circumstance monitoring of power transformer. The action is carried out by supply a low voltage signal of changeable frequencies to the transformer windings and measures both the input and output signals. These two signals give the required response of the ratio is called the transfer function of the transformer from which both the magnitude and phase can be obtained.

Frequency response is change as deliberate by SFRA techniques may indicate a physical change inside the transformer, and then causes of fault recognized and examination is required for root cause analysis.

Key words: Sweep Frequency Response Analyzer Doble M5100, SFRA, Winding Deformation, Power Transformer, SFRA Traces

The method of SFRA is a major go forward in transformer situation investigation. This is a tested method for obtain accurate and repeatable measurements.

The test can be carried out, 1) First to obtain initial signature of the transformer sweep frequency response as a record for the future reference comparison.

2) Periodical measurement as a maintenance check, once in two years.

3) Immediately after a major external shortcuts, especially for faults electrically closer to transformer.

4) Transportation or re-location of transformer.

5) Earthquakes.

6) Pre-commissioning check.

I. INTRODUCTION

III. SWEEP FREQUENCY RESPONSE TEST

This work propose to detect short-circuit faults stuck between two turns in a winding of a transformer &automatic displacement. The transformer is measured to be a compound system of RLC mechanism. Any form of physical harm to the transformer results in the change of this RLC system. These changes are what we are look for and utilize occurrence response to draw attention to these small change in the RLC network within the transformer. For dissimilar frequencies of the RLC network offers different impedance path. Hence, the relocate function at each occurrence is a measure of the effective impedance of the RLC system of the transformer. Any geometrical deformation change in the RLC system, which in turn changes the transfer purpose at different frequencies and hence highlights the locale of concern Power transformers are the most expensive and important part in a high voltage electric power system. It is one of necessary elements and a breakdown of transformer can cause serious problems in electric effectiveness operation. [11].

In the most of the business sweep frequency response activity instruments, the activity task is performed in terms of magnitude (20Ă—log (V2/V1)). The meters are capable of activity corresponding section and electrical resistance magnitudes. The angle between the output voltage V2 and therefore the input Voltage V1 is indicated by the section mensuration.

Commercial francium instruments have 3 leads i.e. source, reference and live (Fig. 1). The supply and reference terminals connected to the input finish whereas the measure terminal is connected to the output finish. In typical 3 section transformers, there area unit high voltage (HV), low voltage (LV) and tertiary windings, and thence various francium connections area unit attainable. Major forms of francium connections area unit mentioned in [3, 5], that embrace end-to-end connections and inter-winding connections. A typical pattern is determined for every take a look at association. take a look at instruments have associate alternating voltage supply, capable of supply a sweep frequency within the vary of twenty cps to five megacycle, with voltage magnitude between two V to twenty four V. The mensuration procedures and precautions to be taken area unit well documented in.[6, 7].

II. SWEEP FREQUENCY RESPONSE ANALYZER The SFRA encompass menstruation the ohm resistance of an electrical device winding over a good vary of frequencies & scrutiny the results with a reference set. SFRA is non-destructive check; Off-Line testing and it are often allotted for any voltage rating of Power electrical device.

The mensuration of SFRA is often a district of normal electrical device maintenance. The SFRA instrument detects the subsequent fault within the power electrical device before break down occur.

1) Disarticulation of Core 2) Twist and displacement of winding 3) Faulty core ground 4) Partial winding collapse 5) Hoop Buckling 6) Broken or loosened clampstructure 7) Shorted turns and open winding.

IV. PROPOSED MODEL

Fig. 1: Proposed model

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SFRA Technique for the Transformer Winding Deformation Analysis (IJSRD/Vol. 3/Issue 09/2015/093)

SFRA technique is now a day, widely used by the electric utilities. It is particularly for detect winding displacements inside the transformer and is based on the fact that incredible occurs in the transformer. The four steps of analysis method are listed: 1) A measurement in the healthy state of the transformer is made.

2) Another measurement is carried out in the supposed fault state.

3) Two responses are compared.

4) Any difference between them means fault has occurred.

Mechanical fault in transformer mostly contribute to the follow reason [9] 1) Winding deformation & winding displacement 2) Movement of clamping pressure 3) Partial collapse of winding 4) Hoop buckling Short and open circuit in winding etc At this juncture following turn faults are analyses by SFRA 1) Inter turn fault 2) Turn to turn fault.

3) Turn to ground fault.

V. METHODOLOGY

VII. PARTIAL DISCHARGE (PD)

A. Frequency Response Analysis (FRA) The loss of mechanical integrity within the sort of winding deformation and core displacement in power transformers will be attributed to the big mechanical device forces attributable to fault currents, winding shrinkage inflicting the discharge of the clamping pressure and through electrical device transportation and relocation. These winding deformation and core displacement if not detected early can generally manifest into a nonconductor or thermal fault. This kind of fault is irreversible with the sole remedy been rewinding of the actual part or a whole replacement of the electrical device. It’s thus imperative to visualize the mechanical integrity of aging transformers sporadically and notably when a brief circuit event to offer early warning of close at hand failure. Thus associate early warning detection technique of such a development is essential. Frequency response analysis is recognized, as been the foremost sensitive diagnostic tool to find even minor winding movement and core displacement [5].

B. Low Voltage Impulse (LVI) method In this technique, a coffee voltage impulse with short front and tail time is applied to at least one finish of the winding.

The winding current is measured with the assistance of a shunt connected at the opposite finish of the winding [6].The input & output responses square measure measured at the same time with digitizers and frequency response is calculated mistreatment quick Fourier remodel technique. the most blessings of the fifty-six technique is its shorter measure time within the order of few seconds, however, the tactic suffers from many disadvantage, form of the impulse, limit the frequency vary. Disposition of check leads affects the repeatability of measure.

C. Sweep Frequency Response Analysis (SFRA) Sweep Frequency Response Analysis (SFRA) could be a tool that may provide a sign of core or winding movement in transformers [7], [8]. During this methodology, measurements square measure performed at frequency are often varied generally from 20Hz - 20MHz. As compared to cardinal methodology, SFRA methodology offers the subsequent initial one is big selection of frequency and smart frequency resolution are often obtained higher signal to noise quantitative relation and therefore the results square measure high.

VI. SIMULATION AND ANALYSIS

Fig. 2: Stages of Partial Discharge It clearly shows the stages of insulation degradation.

Attributable to inadequate insulation style small void is created throughout the service. This small void is growing as huge voids. Just in case of electro mechanical stresses reach the essential price, atomic number 46 seems within void. When atomic number 46 is developed within void conducting trees square measure fashioned outside the void circle that has weak insulation. This treeing impact approaches the alternative conductor. it'll results in breakdown of the insulation medium between 2 electrodes. to achieve this stage it'll take few numbers of years.

Integrity of the insulation of HV instrumentality ought to be confirmed exploitation Partial Discharge Analysis throughout its producing, its commission, and through its life time.

PD is one in all important phenomena to causes the degradation of electrical device winding insulation.

Attributable to this location of atomic number 46 is vital.

There’s the quantity of strategies square measure use to find the atomic number 46 that square measure typical electrical technique, ultrahigh frequency lightweight emission, Chemical strategies, Acoustic emission techniques.

However here location of atomic number 46 by everchanging the alpha values. During this technique useful to location of atomic number 46 in addition as severity of atomic number 46. Severity is obtained from measuring of peak price at the moment of atomic number 46 occurred times. Conjointly ever-changing alpha price that price provides precise location and time needed to location of atomic number 46 at explicit alpha price is a smaller amount. Location of partial discharge is accurately by move wave technique.

VIII. TRANSIENT FAULT Magnetic relays are protecting devices that are wide utilized in the electrical system so as to safeguard the electrical

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SFRA Technique for the Transformer Winding Deformation Analysis (IJSRD/Vol. 3/Issue 09/2015/093)

system from transients and over voltages. However, these devices generate shift transients and noise throughout traditional operation. These shift transients is high enough in magnitude to break instrumentation and cause instrumentation malfunctions. The trendy facility uses many relays throughout the course of daily operation. These relays Generate vast voltage transients. This transient severely affects the electrical device winding [12]. On alternative hand lightning is that the natural phenomena that's happens within the atmosphere between the clouds. Someday this lightning is hit on the cable and trip the instrumentation and power grid.

This will ends up in insulation degradation within the electrical instrumentation. Thanks to this lightning incident can propagates the over current and over voltages within the electrical system. This over voltage is travels to the electrical device through cable severely have an effect on the electrical device. The inhume flip insulation is especially weak to high-frequency oscillation, and so, the study of the distribution of inhume flip. Conjointly to research however can have an effect on totally different form impulse (current and voltage) on electrical device are vital.

IX. CONCLUSION In this effort, a way supported sweep frequency response analysis of the facility electrical device is given which may with success discover faults like winding movement, palladium and Transient fault. On the opposite aspect electrical device faults like palladium and transient wherever occur within the electrical device winding are often simply known victimization traveling wave methodology. In electrical device palladium fault are often specifically placed at the electrical device winding terribly accurately, once the alpha worth is around or over twelve. Transient fault within the electrical device are often known specifically whether the fault occur within the provide finish or load finish. It won’t to avoid ruinous failure in power transformers and conjointly facilitate maintenance engineer to estimate time and price for repairing the transformers when the fault occurred. In future electrical device 3D model needs to be developed by ANSYS. This can be wont to investigate magnetic and Thermal behavior of power electrical device underneath totally different fault condition.

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