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This work extends the wavelet modulation (WM) technique for operating three-phase ($3\phi$), five-level (5L) power electronic converters (PECs). The WM technique is extended by resolution segmentation of the synthesis scale-based linearly combined wavelet functions, which are used as switching signals. The resolution segmentation is created based on the dilation property of synthesis scale-based linearly combined wavelet functions. Each leg of the $3\phi$ VS, 5L dc–ac PEC is operated by two sets of resolution-segmented synthesis scale-based linearly combined wavelet basis functions to produce the voltage of one phase. The extended WM technique is implemented for performance testing, when operating $3\phi$ VS, 5L, diode-clamped and flying-capacitor dc–ac PECs. In this article, Part I, simulation test results are presented and compared with results obtained using the level-shifted pulsewidth modulation, phase-shifted PWM, and space vector modulation. Test results show significant reductions of output harmonics, along with improvements in fundamental components of output voltages and PEC efficiency. [ABSTRACT FROM AUTHOR]

This article presents the implementation and experimental testing of the wavelet-modulation technique for three-phase ($3\phi$) 5-level (5L) power electronic converters (PECs). This version of the wavelet modulation technique is structured as a multiresolution analysis that can support a redundant nonuniform recurrent sampling-reconstruction of three reference-modulating signals. The reconstruction of reference-modulating signals is achieved by sets of resolution-segmented scale-base linearly combined synthesis wavelet basis functions, which are used as switching signals to activate the switching elements of a $3\phi$ , 5L, VS dc–ac PEC. The presented wavelet-modulation technique is implemented in real time using a digital signal-processing board. Switching pulses generated by the extended wavelet-modulation technique are used to operate $3\phi$ , 5L, VS, diode-clamped and flying-capacitor dc–ac PECs. Experimental performance of the tested 5L dc–ac PECs is evaluated, when operated by the presented wavelet modulation, level-shifted pulsewidth modulation (PWM), phase-shifted PWM, and space vector modulation techniques. Experimental tests are conducted for linear, dynamic, and nonlinear loads fed by the tested 5L PECs. Test results show that magnitudes of output voltage fundamental components can be significantly increased, and harmonic distortions can be effectively reduced using the wavelet-modulation technique. These features are further demonstrated by performance comparisons with other techniques under similar operating conditions. [ABSTRACT FROM AUTHOR]

This paper presents the development and performance evaluation of the wavelet modulation technique for single-phase ($1\phi$) cascaded $H$-bridge (CHB) multilevel dc–ac power electronic converters (PECs). The developed technique is based on employing sets of resolution-segmented wavelet basis functions as switching signals, where each set operates one $H$ -bridge. The number of sets of wavelet basis functions is selected to match the number of levels in the output voltage of the $1\phi$ CHB dc–ac PEC. The wavelet modulation for $1\phi$ CHB multilevel dc–ac PECs is implemented for performance evaluation both in simulation and experimentation. The performance of the developed technique is evaluated for linear, nonlinear, and dynamic loads. Simulation and experimental results show significant reduction of output harmonics, along with high magnitude of the fundamental component in the output voltage. The improvements offered by the wavelet modulation technique are further demonstrated through comparisons with the level-shifted and phase-shifted pulse-width modulation techniques under similar loading conditions. [ABSTRACT FROM PUBLISHER]

This paper presents the development and performance evaluation of a direct torque controller (DTC) for permanent-magnet synchronous motor (PMSM) drives fed by a 3\phi 6-pulse wavelet-modulated dc–ac power electronic converters. The developed DTC is designed to adjust the d-q-axis components of stator voltages (vd and vq) of a PMSM in response to changes in the load torque or drive speed. The desired adjustments in vd and vq are achieved by changing the angle $\vartheta$ of a frame created by \text{-hp} PMSM drive system. The performance of the frame-angle-based DTC is investigated for different changes in the command torque and drive speed. Simulation and experimental test results demonstrate stable, fast, and accurate responses that are complimented by negligible sensitivity to variations in the system parameters. [ABSTRACT FROM PUBLISHER]

A digital predictive current controller for a single-phase grid-side power electronics converter employed in photovoltaic (PV) systems is presented in this paper. A disturbance estimator is employed with the controller in order to minimize its sensitivity to any parameter variation, as well as to reject grid-side disturbances. The design of the controller and the estimator are carried out using the pole placement method. The performance of the developed current controller was tested and verified experimentally using a 5.4-kW grid-connected PV system. These experiments are carried out for different levels of power delivered to the grid under different variation in the system parameters. In addition, other controllers used for interconnected PV systems are also tested to highlight the advantages of the developed current controller. The testing results illustrate the capability of the developed current controller to provide accurate, fast, and robust responses with negligible sensitivity to parameters variations and disturbances on the grid side. [ABSTRACT FROM AUTHOR]

In this paper, the performance of a passive anti-islanding method is experimentally tested for three phase (3\phi) cogeneration systems. The tested method is based on determining the wavelet packet transform (WPT) high-frequency subbands present in the d– q-axis components of instantaneous 3\phi, when evaluated at the point of common coupling (PCC). This passive anti-islanding method is founded based on the nature of instantaneous 3\phi apparent powers that have components continuously exchanged between both sides of the PCC. An islanding condition can be considered as a transient disturbance that creates nonperiodic and nonstationary high frequency components in sd and sq. These frequency components can be parameterized by WPT high-frequency subbands, which can provide accurate detection of the islanding condition. The $d$– $q$ WPT-based anti-islanding method is tested for a $3\phi$ cogeneration system under various loading and power delivery conditions. Performance results reveal accurate, fast, and reliable detection and response to the islanding condition. [ABSTRACT FROM AUTHOR]

The growing interest in clean and sustainable electric energy pushes toward increasing the interconnection of wind energy conversion systems (WECSs) to utility grids. The designs of the majority of WECSs employ power electronic converters (PECs), which generally have nonlinear and switched characteristics. The characteristics, operation, and control of PECs in WECSs can result in nonconventional voltage–current behaviors during faults. This paper investigates the voltage–current behaviors during faults that occur in grid-connected WECSs. Two types of WECSs are considered in this paper, which are the doubly fed induction generators and permanent magnet generator based WECSs. The voltage–current behaviors are investigated in experimentations for different faults occurring in different parts of the test grid-connected WECSs. [ABSTRACT FROM PUBLISHER]

Photovoltaic (PV) systems have become a popular type of distributed generation units (DGUs) for small and medium levels of renewable energy generation. When grid connected, these DGUs are designed and operated to deliver electric power to their host grid through power electronic converters. The nonlinear and switched natures, along with the control actions, of these PECs can influence the voltage–current behaviors during faults in grid-connected PV systems. This paper experimentally investigates the voltage–current behaviors during faults occurring in grid-connected PV systems. Results of these investigation show that voltages and currents at the point-of-common-coupling (PCC) experience changes in their magnitudes and harmonic distortions due to faults occurring on both sides of PCC. These results can be incorporated in the improvement of the accuracy and reliability of protective devices used for grid-connected PV systems. [ABSTRACT FROM PUBLISHER]

The switching pulses of the wavelet modulation technique are generated as sets of dilated and shifted scale-based linearly combined synthesis wavelet functions. The duration and location of each switching pulse are set by the scale (resolution level) at which its associated synthesis wavelet function is generated. In this paper, a novel controller is developed and tested for three phase (3\phi) voltage source (VS) six-pulse wavelet-modulated ac–dc converters. The proposed controller is structured to adjust the maximum value reached by the scale. This maximum value, J, is adjusted based on two angles. The first angle, \thetaI, maps changes in the 3\phi supply voltages to adjustments in J, while the second angle, \thetaO, maps changes in the dc output voltage to adjustments in J. The net adjustment in J is optimized based on the mapped changes by \thetaI and \thetaO. The optimal resolution-level controller is implemented in order to evaluate its performances for operating 3\phi VS six-pulse ac–dc converters. The performances of the proposed controller are tested when the converter is supplied with balanced, unbalanced, and distorted 3\phi voltages for feeding static and dynamic loads. Test results demonstrate fast and accurate responses, stable functioning, and good dynamics to ensure that the output dc voltage follows its command value for different supply and loading conditions. [ABSTRACT FROM PUBLISHER]

This paper presents the implementation and performance testing of the wavelet modulation technique for operating three phase, voltage source (VS), six-pulse ac–dc converters. The wavelet modulation technique is realized by a nondyadic-type multiresolution analysis (MRA), which is constructed using sets of dilated and translated scale-based linearly combined wavelet basis functions. A dc reference signal is processed using this MRA, where three sets of groups of nonuniform recurrent samples are created by the analysis stage. The synthesis stage of the nondyadic MRA reconstructs the dc reference signal using three sets of dilated and translated scale-based linearly combined synthesis wavelet basis functions, which are used to activate the switching elements of the ac–dc converter. Simulation and experimental performances of the 3\phi ac–dc converter, that is, operated by the wavelet modulation technique, are investigated for supplying static and dynamic load types. Performances of the 3\phi wavelet modulated ac–dc converter are also investigated for unbalanced input 3\phi voltages. Simulation and experimental results show that high magnitude of output dc components, and significant reductions of input and output harmonic components of the 3\phi VS ac–dc converter can be accomplished using the wavelet modulation technique. These improvements in the performances of 3\phi ac–dc converters are further demonstrated through comparisons with the pulse-width and space-vector modulation techniques under similar conditions of loading and 3\phi input voltages. [ABSTRACT FROM AUTHOR]

This paper presents the development, implementation, and performance testing of a permanent-magnet generator (PMG)-based wind energy conversion system (WECS) for grid-connected applications. The grid-connected operation is constructed using the new three-phase resolution-level-controlled wavelet-modulated inverter. The output of the wind generator is fed to a switch-mode ac–dc converter, where the dc voltage is controlled to ensure extracting power from the wind under variable wind speed conditions in order to meet the grid active and reactive power demands. The resolution-level control of the grid-side inverter is designed as a current controller for adjusting active and reactive powers delivered to the grid. The proposed WECS is implemented both in software and hardware for performance testing on a direct-drive 6-kW laboratory PMG operated with variable speed. Test results demonstrate that an accurate control of the dc voltage on the generator side ensures adjusting the generator speed to extract power at each wind speed in order to meet the demand active and reactive power delivery to the grid. Also, test results show significant abilities of the resolution-level controller to initiate fast and accurate adjustments in the active and reactive powers delivered to the grid in order to follow any changes in their demand values under variable wind speed. [ABSTRACT FROM AUTHOR]

This paper presents the real-time implementation and experimental performances of the wavelet-modulation technique for single-phase voltage-source (VS) inverters. The wavelet-modulation technique is realized through constructing a nondyadic-type multiresolution analysis, which supports sampling of a sinusoidal reference-modulating signal in a nonuniform recurrent manner, then reconstructing it using the inverter-switching actions. The required nonuniform recurrent sampling is carried out by using dilated and translated sets of wavelet basis functions, which are generated by the scale-base linearly combined scaling function. The reconstruction of the sampled signal is accomplished by using dilated and translated sets of wavelet basis functions, which are generated by the scale-base linearly combined synthesis scaling function. The dilated and translated sets of wavelet basis functions used in the reconstruction are employed as switching signals to activate the inverter-switching elements. The wavelet-modulation technique is implemented in real time by using a digital signal processing board to generate switching pulses for a single-phase VS H-bridge (four-pulse) inverter. Experimental performances of the single-phase inverter, which is operated by the wavelet-modulation technique are investigated while supplying linear, dynamic, and nonlinear loads with different frequencies. Experimental test results show that high magnitude of fundamental components and significantly reduced harmonic contents of the inverter outputs can be achieved using the wavelet-modulation technique. The efficacy of the developed modulation technique is further demonstrated through performance comparisons with the pulsewidth- and random-pulsewidth-modulation techniques for similar loading conditions. [ABSTRACT FROM AUTHOR]

This paper presents the analysis, development, and implementation of a wavelet modulation (WM) technique for three-phase voltage-source (VS) six-pulse inverters. The WM technique is based on sampling three continuous-time (CT) sinusoidal reference modulating signals in a nonuniform recurrent manner using three sets of scale-based linearly combined wavelet basis functions. These CT signals are recovered from their samples by a three-phase VS six-pulse inverter, which is activated by three sets of synthesis scale-based linearly combined wavelet basis functions. Each set of synthesis basis functions is generated for activating one leg of the three-phase inverter in order to recover one CT reference modulating signal. The WM technique is implemented for both simulation and experimental performance testing. The performances of the WM technique are compared with those obtained using the space vector modulation, random pulsewidth modulation, and hysteresis band current control techniques under the same loading conditions. Simulation and experimental test results show that the proposed WM technique is able to switch a three-phase VS six-pulse inverter to produce outputs with significantly improved fundamental components and low harmonic contents. [ABSTRACT FROM PUBLISHER]