Virtual Instrument for Lightning Impulse Tests
TL;DR: In this paper, an objective formulation of the impulse analysis problem from a signal analysis viewpoint is proposed, where the winding response is quintessentially that of a deterministic network to a finite energy signal, with breakdown and partial discharge being inherently nonlinear events.
Abstract: We propose an objective formulation of the impulse analysis problem from a signal analysis viewpoint. The winding response is quintessentially that of a deterministic network to a finite energy signal, with breakdown and partial discharge being inherently nonlinear events. A significant improvement to the acquisition of waveforms is demonstrated by a virtual instrument approach. It retains the advantages of the time- and frequency-domain methods. The drawbacks of the transfer function method are highlighted and a new piecewise linear approach is proposed for analysis. Experiments on a discrete lumped parameter model of the winding are used to validate the PXI based instrument.
Citations
More filters
TL;DR: In this article, the limitation of time domain correlation method in locating partial discharge (PD) in transformer windings is found out, and frequency domain correlation with Gram Schmidt orthogonalization is proposed.
Abstract: Partial discharge (PD) is one of the sources of insulation failures in Power transformers. Knowledge of the PD source locations are important for transformer maintenance and repair. Due to the complex structure of the transformer, it is very difficult to locate the PD accurately in transformer winding. Correlation methods are applied to locate the PD source across the winding. The PD across parts of the winding are simulated by applying voltage pulse across the sections. The winding response for a reference PD impulse across transformer sections are taken as base for correlation and correlated with winding response of PD impulse across any section with different PD pulse widths. In this paper the limitation of time domain correlation method in locating PD in transformer windings is found out. To overcome the limitation of time domain correlation method, frequency domain correlation with Gram Schmidt orthogonalization is proposed. Simulation and experiments are performed on layer, continuous disc and interleaved windings to prove the feasibility of the proposed method.
39 citations
Cites background from "Virtual Instrument for Lightning Im..."
...From the extensive literature survey on the PD pulse width, it is found that the PD pulse width ranges between 1ns to few μs [15, 16]....
[...]
TL;DR: In this article, the authors propose new techniques for fault detection based on continual assessment during the test. They include voltage comparison, current comparison, and real/reactive power measurements, which are validated on a number of models including a voltage transformer and a distribution transformer winding.
Abstract: The ability of a transformer to withstand the dynamic effects of a short circuit test is conventionally evaluated by a measurement of short circuit reactance before and after the test. We propose new techniques for fault detection based on continual assessment during the test. The methods are based on the comparative null method for accuracy measurement in instrument transformers. They include voltage comparison, current comparison and real/reactive power measurements. High resolution sampling based acquisition systems are used to compute changes on a cycle-to-cycle basis. The proposed methods are validated on a number of models including a voltage transformer and a distribution transformer winding. They would be useful for designers in assessing events leading to failure in a more transparent manner.
37 citations
Cites background from "Virtual Instrument for Lightning Im..."
...A full description of the virtual instrument is available in [20]....
[...]
TL;DR: In this paper, a tapped transformer is designed and test platforms are built to compare winding diagnoses using the impulse wave and sweep frequency response analysis methods by recording voltage responses on both the high and low-voltage sides and calculating the respective transfer functions.
Abstract: Monitoring of winding faults is the most important item used to determine the maintenance status of a transformer. Commonly used methods for winding-fault diagnosis require the transformer to exit operation before testing and an external exciting signal, whether the transformer is malfunctioning or not. However, if an overvoltage signal can be regarded as a broadband excitation source for fault diagnosis, then the interference caused by signal injection can be eliminated without the need for additional pulse or impulse signals. In this paper, a tapped transformer is designed and test platforms are built to compare winding diagnoses using the impulse wave and sweep frequency response analysis methods by recording voltage responses on both the high- and low-voltage sides and calculating the respective transfer functions. Based on comparison of statistical indicators, it is found that the sensitivities of both methods are similar for detecting conditions of winding-ground and winding-interlayer short circuits. It is concluded that it is feasible to use a transient overvoltage monitoring system for winding-fault diagnosis.
24 citations
TL;DR: A technique based on an Archimedean copula is proposed to find the location of a Partial Discharge source in a transformer winding and demonstrates that the proposed approach is capable of achieving an accurate prediction of the locations of the PD source.
Abstract: Precise localization of a Partial Discharge (PD) source inside a winding is one of the important tasks for early detection and prevention of catastrophic failure of a transformer. However, due to the highly complex structures of the windings and statistical nature of PD, the exact location of a PD source is quite difficult to discover. In this paper, a technique based on an Archimedean copula is proposed to find the location of a PD source in a transformer winding. The winding responses to the PD signals of known pulse-widths applied at all the sections are taken as reference data. Further, the winding responses, obtained from the PD pulses of random shapes and magnitudes applied across various sections of the winding, are taken as test data. To predict the location of the test signals, the best-fit copula and its parameters are established using the reference and test data. The maximum value of log-likelihood between the reference data and the test signal indicates the location of the PD source. Firstly, simulation case-studies are conducted to demonstrate how the proposed approach can be implemented to locate the PD source. The results of the proposed method are then compared with the time-domain and frequency-domain based correlation techniques. Finally, the proposed method is tested with experimental data acquired from a laboratory scale model of the transformer winding. The simulation and experimental results demonstrate that the proposed approach is capable of achieving an accurate prediction of the location of the PD source.
19 citations
Cites background from "Virtual Instrument for Lightning Im..."
...In general, pulse-widths of PD signals lie between 1 ns to a few μs [30-31]....
[...]
TL;DR: In this article, statistical techniques are used to locate the partial discharge in transformer windings, and the experimental studies are performed on a 22-kV prototype interleaved winding to prove the feasibility of the methods.
Abstract: To locate the partial discharge in transformer windings, statistical techniques are proposed. The experimental studies are performed on a 22-kV prototype interleaved winding to prove the feasibility of the methods.
17 citations
Cites background from "Virtual Instrument for Lightning Im..."
...Generally, PDs are very short pulses of durations from tens of nanoseconds to 5 s [2]....
[...]
References
More filters
19 Oct 2003
TL;DR: In this paper, the authors have used a new technique to simulate such faults, and experimentally obtained waveforms are used to investigate the suitability of wavelets to detect faults during impulse testing.
Abstract: The impulse test on power transformers simulates the conditions that exists in service when a transformer is subjected to an incoming high voltage surge due to lightning or other disturbances on the associated transmission line. There have been several studies on the application of wavelets to identify faults during impulse testing. Most of these studies have utilized simulated waveforms in which the fault is introduced by a suitable mathematical model. In this paper the authors have used a new technique to simulate such faults. Experimentally obtained waveforms are used to investigate the suitability of wavelets to detect faults during impulse testing and this paper presents preliminary results of this research work.
4 citations
TL;DR: In this paper, a fuzzy logic approach is proposed for identification and classification of faults based on records obtained during impulse tests on transformers, where the outputs of three filters form the basis of identification.
Abstract: A fuzzy logic approach is proposed for identification and classification of faults based on records obtained during impulse tests on transformers. The outputs of three filters form the basis of identification. Experiments are performed on a physical lumped parameter model of a winding to identify breakdown, partial discharge and the presence of non-linear element within the winding. The location of breakdown can also be estimated.
3 citations
"Virtual Instrument for Lightning Im..." refers background in this paper
...The recognition of these faults, including identification of nonlinear elements within, can be automated based on the responses obtained in the virtual instrument [24]....
[...]
01 Jan 2006
2 citations
"Virtual Instrument for Lightning Im..." refers background in this paper
...As far as identification of breakdown is concerned, the response across the first filter F1 is significant [18]....
[...]
01 Nov 2005
TL;DR: In this article, the authors proposed an adaptive architecture that characterizes all these events in a unified manner, based on the PXI hardware with necessary software developed under LABVIEW environment.
Abstract: Several phenomena in transformers are best analyzed in the frequency domain when energized by broadband excitation. These include dielectric behavior to lightning impulse, winding deformation during transport and structural failure during short circuit tests. We propose an adaptive architecture that characterizes all these events in an unifying manner. The developed instrument is based on the PXI hardware with necessary software developed under LABVIEW environment. Experimental results using the developed instrument are reported to demonstrate its versatility.
1 citations
Additional excerpts
...deformations during short-circuit tests [25]....
[...]