A new frequency response analysis method for power transformers

Vaessen, Peter; Hanique, E.

doi:10.1109/61.108932

Cited by 88 publications

(19 citation statements)

References 3 publications

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“…Since the position of the PD source inside the apparatus is, in general unknown, PD signal shapes are distorted in an unpredictable way depending on the location and the design of the tested object. In particular, a signal shape can show two modes: a "pulse mode" that arrives at the terminal with a delayed risetime and mainly contains the higher frequency components; a "slow mode" composed of an oscillating tail due to partwinding resonances, mismatched impedances and traveling wave reflections that affect the damping coefficients, [55,56]. Consequently, pulses coming from different sites are often characterized by different shapes which can be very useful to separate contributions in PD patterns due to multiple sources.…”

Section: Pd Signal Propagation and Detectionmentioning

confidence: 99%

Classification and separation of partial discharge signals by means of their auto-correlation function evaluation

Contin

Pastore

2009

IEEE Trans. Dielect. Electr. Insul.

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This paper describes a K-Means Clustering classification algorithm for the separation of Partial Discharge (PD) signals and pulsating noise due to multiple sources occurring in practical objects. It is based on the comparison of the Auto-Correlation Function (ACF) of the recorded signals assuming that the same source can generate signals having similar ACF while ACF differ when signals with different shapes are compared. The ACF has been selected for its capability of well summarize both time-and frequency-dependent features of the signals. A correlation index that presents the best compromise between strong and weak discrimination among pulses, has been selected out of different distance measurements. The final result of the algorithm is a set of classes containing signals having similar shape which can be processed successively for signal source identification. Meaningful applications of the proposed algorithm are also reported. Improvements in separation effectiveness can enhance the clearness of the PD patterns and, consequently, the quality of the defect identification.

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Section: Pd Signal Propagation and Detectionmentioning

confidence: 99%

Classification and separation of partial discharge signals by means of their auto-correlation function evaluation

Contin

Pastore

2009

IEEE Trans. Dielect. Electr. Insul.

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“…These defects can appear as a result of shocks during transportation or electromagnetic forces that occur during short-circuit. This technique has been remarkably developed in power transformers since its appearance [3] more than twenty years ago, until the development of standards of application as [4]. It is based on the analysis of the equivalent impedance of the winding under test, in the frequency domain.…”

Section: Introductionmentioning

confidence: 99%

Field-winding fault detection in synchronous machines with static excitation through frequency response analysis

Blánquez

Platero

Rebollo

et al. 2015

International Journal of Electrical Power & Energy Systems

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a b s t r a c tFrequency Response Analysis is a well-known technique for the diagnosis of power transformers. Currently, this technique is under research for its application in rotary electrical machines. This paper presents significant results on the application of Frequency Response Analysis to fault detection in field winding of synchronous machines with static excitation. First, the influence of the rotor position on the frequency response is evaluated. Secondly, some relevant test results are shown regarding ground fault and inter-turn fault detection in field windings at standstill condition. The influence of the fault resistance value is also taken into account. This paper also studies the applicability of Frequency Response Analysis in fault detection in field windings while rotating. This represents an important feature because some defects only appear with the machine rated speed. Several laboratory test results show the applicability of this fault detection technique in field windings at full speed with no excitation current.

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“…Hereby it is assumed, that the main cable losses are caused by the skin effect and the transformer can still be described as a capacitor. However, at higher frequencies dielectric losses in the cable can start to become important, and also the transformer may show some resonances [9]. The impedances applied at both cable ends were chosen equal: 1 nF, 10 nF (typical for load by transformer); 10 and 100 (typical for load by leaving cables).…”

Section: Coupling Efficiencymentioning

confidence: 99%

Effect of Cable Load Impedance on Coupling Schemes for MV Power Line Communication

Wouters

Wielen

Veen

et al. 2005

IEEE Trans. Power Delivery

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Abstract-Coupling of carrier wave frequencies up to 95 kHz (within the European CENELEC A-band) for online diagnostic data transfer in medium voltage cables is studied. Inductive and capacitive signal coupling is considered not only on basis of technical performance, but also on basis of practical aspects. The effectiveness of coupling schemes depends on the impedances of substation equipment at the cable terminals. The frequency response of a 10-kV, 400-kVA three-phase cast resin distribution transformer is investigated. In the frequency range of interest, the behavior is well described by a capacitance of typically 1 nF. The signal transfer over a 4-km paper cable, terminated by various load impedances to mimic real equipment is studied. From the results it is concluded that for inductive coupling performance within the CENELEC A-band may be sufficient, except for substations at the end of a grid. Transferring signals containing frequencies up to several megahertz, which is already required for synchronization of partial discharge detection and location equipment, is feasible under all conditions. Measurements on life substations indicate that up to these frequencies substation components can still be accurately modeled as lumped circuit impedances.

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A new frequency response analysis method for power transformers

Cited by 88 publications

References 3 publications

Classification and separation of partial discharge signals by means of their auto-correlation function evaluation

Classification and separation of partial discharge signals by means of their auto-correlation function evaluation

Field-winding fault detection in synchronous machines with static excitation through frequency response analysis

Effect of Cable Load Impedance on Coupling Schemes for MV Power Line Communication

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