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A User’s Guide

In this paper, the authors propose a method for the diagnosis of rotor bar failures in induction machines, based on the analysis of the stator current during the startup using the discrete wavelet transform (DWT). Unlike other approaches, the study of the high-order wavelet signals resulting from the decomposition is the core of the proposed method. After an introduction of the physical and mathematical bases of the method, a description of the proposed approach is given; for this purpose, a numerical model of induction machine is used in such a way that the effects of a bar breakage can clearly be shown, avoiding the influence of other phenomena not related with the fault. Afterward, the new diagnosis method is validated using a set of commercial induction motors. Several experiments are developed under different machine conditions (healthy machine and machine with different levels of failure) and operating conditions (no load, full load, pulsating load, and fluctuating voltage). In each case, the results are compared with those obtained using the classical approach, based on the analysis of the steady-state current using the Fourier transform. Finally, the results are discussed, and some considerations about the influence of the DWT parameters (type of mother wavelet, order of the mother wavelet, sampling rate, or number of levels of the decomposition) over the diagnosis are done

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Validation of a new method for the diagnosis of rotor bar failures via wavelet transform in industrial induction machines

This paper deals with fault diagnosis of induction machines based on the discrete wavelet transform. By using the wavelet decomposition, the information on the health of a system can be extracted from a signal over a wide range of frequencies. This analysis is performed in both time and frequency domains. The Daubechies wavelet is selected for the analysis of the stator current. Wavelet components appear to be useful for detecting different electrical faults. In this paper, we will study the problem of broken rotor bars, end-ring segment, and loss of stator phase during operation.

Fault Diagnosis in Industrial Induction Machines Through Discrete Wavelet Transform

Review of energy storage services, applications, limitations, and benefits

In this paper, a general methodology based on the application of discrete wavelet transform (DWT) to the diagnosis of the cage motor condition using transient stator currents is exposed. The approach is based on the identification of characteristic patterns introduced by fault components in the wavelet signals obtained from the DWT of transient stator currents. These patterns enable a reliable detection of the corresponding fault as well as a clear interpretation of the physical phenomenon taking place in the machine. The proposed approach is applied to the detection of rotor asymmetries in two alternative ways, i.e., by using the startup current and by using the current during plugging stopping. Mixed eccentricities are also detected by means of the transient-based methodology. This paper shows how the evolution of other non-fault-related components such as the principal slot harmonic (PSH) can be extracted with the proposed technique. A compilation of experimental cases regarding the application of the methodology to the previous cases is presented. Guidelines for the easy application of the methodology by any user are also provided under a didactic perspective.

A General Approach for the Transient Detection of Slip-Dependent Fault Components Based on the Discrete Wavelet Transform

At sea, the electrical power system of a ship can be considered as an islanded microgrid. When connected to shore power at berth, the same power system acts as a grid connected microgrid or an extension of the grid. Therefore, ship microgrids show some resemblance to terrestrial microgrids. Nevertheless, due to the presence of large dynamic loads, such as electric propulsion loads, keeping the voltage and frequency within a permissible range and ensuring the continuity of supply are more challenging in ship microgrids. Moreover, with the growing demand for emission reductions and fuel efficiency improvements, alternative energy sources and energy storage technologies are becoming popular in ship microgrids. In this context, the integration of multiple energy sources and storage systems in ship microgrids requires an efficient power management system (PMS). These challenging environments and trends demand advanced control and power management solutions that are customized for ship microgrids. This paper presents a review on recent developments of control technologies and power management strategies proposed for AC ship microgrids.

/pdf/ac-ship-microgrids-control-and-power-management-optimization-21ikqkc9u1.pdf

AC Ship Microgrids: Control and power management optimization

This paper deals with the problem of estimation of voltage and current spectrum, especially harmonics, in the field of electrical power engineering. After description of hitherto used methods, a method of the combined wavelet-Fourier spectrum analysis has been proposed. The method consists in applying the wavelet transform for samples of the original signal, then using digital Fourier transform to the results for spectrum extraction. As a result, the significantly decreased number of needed multiplications is observed. A comparison of the method and fast Fourier transform, as well as the recently introduced wavelet packet decomposition, has been carried out. Finally, the results of experimental research have been shown and commented on. During research, various kinds of wavelet "mothers" and varying filter length have been taken into consideration.

Hybrid wavelet-Fourier spectrum analysis

This paper deals with a problem of fast and reliable waveform disturbances recognition. It means real-time detection and evaluation of different kinds of waveform distortions such as harmonics, interharmonics, as well as transients and notching. In this paper, the problems of sampling frequency, a resulting number of samples and a complementary application of Fourier transform and a wavelet transform have been described. The main focus of this paper has been placed on harmonics and harmonic subgroups analysis. However, there is an assumption that harmonics are to be measured concurrently with transient and notching by a single dedicated device. All analyses have been carried out for the real voltages waveforms registered in ship and land electric power systems

Hybrid Wavelet–Fourier Method for Harmonics and Harmonic Subgroups Measurement—Case Study

Estimator-analyzer of power quality: Part I – Methods and algorithms

This paper discusses various methods of calculating coefficients in Fourier series. In particular, the methods recommended in IEC Standard 61000-4-7 and the methods applied in commercial power quality analyzers were investigated. The analysis was carried out for a simulated signal and based on the real voltage registered in an isolated electric power system. It consists of uncertainty evaluation and computational complexity assessment. In the latter case, a digital signal processor simulator and software developed by the author were used. Finally, suggestions for constructors of future power quality analyzers were formulated.

Tomasz Tarasiuk

Papers

AC Ship Microgrids: Control and power management optimization

Hybrid wavelet-Fourier spectrum analysis

Hybrid Wavelet–Fourier Method for Harmonics and Harmonic Subgroups Measurement—Case Study

Estimator-analyzer of power quality: Part I – Methods and algorithms

Comparative Study of Various Methods of DFT Calculation in the Wake of IEC Standard 61000-4-7