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This article presents the performance evaluation of the frame-angle-based (FAB) direct torque controller (DTC) for 3φ induction motor drives (IMDs), which are fed by 3φ six-pulse wavelet-modulated (WM) dc–ac power electronic converters (PECs). The tested DTC is designed to adjust the de- and qe-axis components of the voltages (veds and vegs) applied to a 3φ IMD. The adjustments in veds and vegs are created in response to changes in the load torque, command torque, drive speed, and/or system parameters. Desired adjustments in veds and vegs are set by regulating the angle θ of the frame created by veds and vegs. This frame produces reference modulating signals that are required to generate WM switching pulses for operating the 3φ dc–ac PEC in the IMD. The complete IMD system, incorporating the FAB-DTC, is implemented for a 10-hp IMD system for performance evaluation. Tests of the FAB-DTC for the 10-hp IMD are conducted for various changes in the load torque, command torque, drive speed, and system parameters. Simulation and experimental test results demonstrate fast, accurate, reliable, and dynamic responses with minor sensitivity to variations in system parameters. [ABSTRACT FROM AUTHOR]

This article presents and tests the performance of a digital differential protection for three-phase (3φ) converter transformers. The proposed digital differential protection is developed to comply with the ANSI 87T protection procedure. The presented protection is featured with fault detection based on the energy contents of the high-frequency subbands of the d−q axis components of differential currents. Desired energy contents are extracted using the phaselet transform (PHT), which can process signals without sensitivity to the variations in their phase shifts. Energy contents of the high-frequency subbands offer accurate, fast, and reliable detection, and identification of internal faults in any part of a 3φ converter transformer. The d−q PHT-based digital differential protection is implemented for performance evaluation using different 3φ converter transformers, when feeding controlled rectifier units. Performance results demonstrate accurate, fast, and reliable detection, and response to different types of fault, and nonfault events. Response features of the developed differential protection are complimented with simple implementation, reduced computations, and minor sensitivity to phase shifts, fault location, and loading levels. [ABSTRACT FROM AUTHOR]

This paper presents the online implementation and performance evaluation of the phaselet-based method for detecting electric faults in induction motor drives (IMDs). The online implementation of tested fault detection method is achieved using a digital signal-processing board, where the inputs are the 3φ stator currents and the output is a trip signal. The desired fault feature is extracted using six digital high-pass filters, whose coefficients have been obtained using phaselet basis functions that are generated by the biorthogonal 2.1 scaling function. The performance of the phaselet-based fault detection method is tested for two different IMDs that are fed across-the-line and through a frequency drive system, when operated at different loading levels. Experimental test results show accurate, reliable, and fast fault detection, along with negligible sensitivity to the speed, loading levels, IMD ratings, and fault type. [ABSTRACT FROM PUBLISHER]

This paper presents the analysis and development of a new method for electric fault detection in induction motor drives. The proposed method is based on extracting the magnitudes and phases of the high-frequency subband (HFSB) contents present in the d - q-axis components of the stator currents (id and iq) in an induction motor. The desired magnitudes and phases are extracted by processing id and iq using phaselet frames that are realized by a modulated filter bank. This filter bank is designed using six digital high-pass filters, whose coefficients are determined by biorthogonal phaselet basis functions. Extracted HFSB contents provide signature information that can offer accurate and fast detection of faults. The phaselet-based electric fault detection method has been made into a procedure for digital implementation. The performance of the proposed method is evaluated offline for collected stator currents from two different induction motor drives under different operating conditions. Offline test results show accurate, reliable, and fast detection of electric faults, with minor sensitivity to the ratings, loading levels, and type and location of faults. [ABSTRACT FROM PUBLISHER]

The design and implementation of a Virtual Electric Power Transmission Line Lab for undergraduate curricula is introduced in this paper. The aim of the virtual laboratory is to enhance learning and teach students the basis and characteristics of the power transmission line model under different conditions in a virtual interface before entering the field. The user can realize various tests, such as short circuit, no-load, load and fault tests, to develop an understanding of the model behaviors, effects of changes in the model parameters, load and connections. The proposed Virtual Electric Power Transmission Line Lab is developed in the MATLAB graphical user interface (GUI) environment. The proposed virtual lab has been implemented in the Power Systems Lab taught at the Department of Electrical and Electronics Engineering at Karadeniz Technical University as part of the undergraduate curriculum. A survey of the students who took the lab course has been conducted, and the responses are included in this paper. [ABSTRACT FROM AUTHOR]