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Energies 2016, 9(11), 933;

Analysis of Power Quality Signals Using an Adaptive Time-Frequency Distribution

Department of Electrical Engineering, Foundation University, Islamabad 44000, Pakistan
Department of Electrical Engineering, Federal Urdu University of Arts Science and Technology, Islamabad 44000, Pakistan
Department of Electrical Engineering, COMSATS Institute of Information Technology, Islamabad 44000, Pakistan
SnT -, University of Luxembourg, Kirchberg, Luxembourg 1359, Luxembourg
Author to whom correspondence should be addressed.
Academic Editor: Jose Fernando Alves da Silva
Received: 19 August 2016 / Revised: 17 October 2016 / Accepted: 26 October 2016 / Published: 9 November 2016
(This article belongs to the Special Issue Power Electronics in Power Quality)
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Spikes frequently occur in power quality (PQ) disturbance signals due to various causes such as switching of the inductive loads and the energization of the capacitor bank. Such signals are difficult to analyze using existing time-frequency (TF) methods as these signals have two orthogonal directions in a TF plane. To address this issue, this paper proposes an adaptive TF distribution (TFD) for the analysis of PQ signals. In the proposed adaptive method, the smoothing kernel’s direction is locally adapted based on the direction of energy in the joint TF domain, and hence an improved TF resolution can be obtained. Furthermore, the performance of the proposed adaptive technique in analyzing electrical PQ is thoroughly studied for both synthetic and real world electrical power signals with the help of extensive simulations. The simulation results (specially for empirical data) indicate that the adaptive TFD method achieves high energy concentration in the TF domain for signals composed of tones and spikes. Moreover, the local adaptation of the smoothing kernel in the adaptive TFD enables the extraction of TF signature of spikes from TF images, which further helps in measuring the energy of spikes in a given signal. This new measure can be used to both detect the spikes as well as to quantify the extent of distortion caused by the spikes in a given signal. View Full-Text
Keywords: time-frequency; power quality; power signals; smoothing; distribution time-frequency; power quality; power signals; smoothing; distribution

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Khan, N.A.; Baig, F.; Nawaz, S.J.; Ur Rehman, N.; Sharma, S.K. Analysis of Power Quality Signals Using an Adaptive Time-Frequency Distribution. Energies 2016, 9, 933.

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