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This paper realizes a high power factor, high reliability, and low cost PMSM drive system with small DC-link capacitor. Compared with conventional bulky electrolytic capacitor for the regulation of DC-link voltage, a small-size film capacitor with capacitance reduction to 1% is used to realize a seneorless PMSM drive with high power factor, high reliability, and high compactness. To overcome high...
In railway traction applications, due to the limitation of switching frequency and the attempt to fully utilize the DC-link voltage, the traction inverters usually work in six-step (or quasi-square-wave) mode under heavy load or high frequency condition. Meanwhile, DC-link voltage fluctuation, stemming from a common single-phase grid-side power supply, has a great impact on the drive system. To maintain...
Although the wireless power transfer (WPT) has been used in a wide range of areas, there are many difficulties with the development of WPT. The load voltage quality problem caused by the high susceptibility of the delivered power to the surrounding is still a key issue to be solved. To guarantee a high quality of dc load voltage in WPT system, this paper proposes a novel voltage control strategy based...
The paper addresses the problem of fault detection in an unbalanced microgrid with distributed generators, using algorithms based on harmonic estimation: Wavelet Transform (WT), Fast Fourier Transform (FFT) and Reduced Fast Fourier Transform (RFFT). Simulations were carried out in the MATLAB/SimPowerSystems environment. Modified IEEE13 bus system with distributed generation was used. Experimental...
This paper reviews the power quality challenges associated with intermittency of grid connected PV systems and reviews energy storage systems and inverter control techniques that can be utilized to mitigate the fluctuations and power quality issues effectively. This review forms part of a future study which will incorporate a hybrid supercapacitor and battery energy storage system for ramp rate control,...
This paper presents prediction of voltage flicker (Short Term Flicker and Long Term Flicker) on Grid Connected Photovoltaic (GCPV) power system towards Malaysia climate variations (solar irradiance) by using Mathematical model. The actual and prediction data measurement were analyzed under three different types of GCPV systems that installed in Green Energy Research Centre (GERC), University of Technology...
The voltage sag and swell are the important problems that discussed in the grid voltage quality. In this paper, a new compensation structure based on dynamic voltage restorer (DVR) and photovoltaic (PV) system is proposed. PV system is supported by an energy storage element (battery). Also, the operating of PV system is controlled by incremental conductance (IC) algorithm to maximum power point tracking...
Unpredictable power quality (PQ) events such as, balanced and unbalanced voltage sag/swell, frequency shift, phase jump and harmonic distortions in the utility grid voltage drastically affects the performance of a grid interfaced distributed generation (DG) systems due to unreliable synchronization. This paper presents adaptive synchronization based dq-current control technique for three-level NPC...
This paper proposes a two-stage three-level DC/AC converter, which consists a three-level inter-leaved dc/dc boost converter in the first stage, and a three-level neutral-point-clamped (NPC) inverter in the second stage. The boost converter regulates variable and/or wide-range dc source, then provides suitable and stable dc voltage to the NPC inverter. The NPC inverter generates variable frequency...
This paper focuses on an analysis on compatibility between power grid quality voltage and dispatchable photovoltaic plant integration. In this order, based on a simulation, voltage dips have been calculated on the bus bars of a test system (IEEE-RTS). The method for voltage dip estimation used in this paper provides the frequency of voltage dips, due to symmetrical and unsymmetrical faults in the...
This paper proposes a novel control strategy for electrolytic capacitor-less quasi-Z-source inverter, which fed adjustable-speed drive (ASD) system with almost unit input power factor. The system has no shoot through issues and gains high reliability. By using E-caps-less topology, the life time can be greatly increased. In order to guarantee the high power factor and the ability of resisting grid...
A Single Phase Dynamic Voltage Restorer (DVR) based on five-level ground point shifting multilevel inverter topology has been proposed in this paper. The proposed inverter has a floating ground point. Therefore, by shifting the ground point, it is observed that the inverter circuit gives five output voltage levels from single DC voltage source. This configuration uses less number of switches compared...
India, being a tropical country has rich solar resource. Hence, with a strong commitment towards increasing its renewable share, India has set a target to install 100 GW of solar generation capacity by 2022 in which 40 GW would be grid-connected rooftop solar photovoltaic (PV) systems. This paper examines the potential, importance, foreseen challenges, outlook, and technical impact due to large-scale...
With the integration of DGs to utility side, drastic changes in fault current occurs across the system at different locations in a microgrid. In this paper different types of faults in microgrid system are investigated through simulation using Simulink-MatLab. The impacts of inverter interfaced DGs on fault current and importance of adaptive protection issues for islanded and utility microgrid are...
In this work a three-phase power supply to emulate voltage disturbances that occur in an electrical network is presented. The type of disturbances that can be generated are voltage drop (voltage sags), over voltage (voltage swell). To maintain the value of the disturbance is necessary to implement a close loop with a control technique on it. Three control schemes were probed in this work: PI, PID...
This paper introduces a predictive voltage controller for multilevel inverter used in Dynamic Voltage Restorer, which is able to protect a sensitive load against grid voltage sags dynamically. The compensated voltages are obtained by using Phase-Lock Loop to detect the phase and the magnitude of the grid voltage then compare to the load reference voltage. A three-phase NPC inverter with output LC...
Dc-link voltage fluctuation, originated from the single-phase power supply, has a significant impact on the railway traction drive system. This impact is of importance for stable operation and better performance. Meanwhile, the high-power and limited space of traction inverter requires low-switching frequency modulation techniques. The influence on performance of the traction drive system under these...
With the focus on environmental sustainability and energy security, policy makers and electric utility planners are looking at renewable energy both as supplements and alternatives. But such generation sources have their own challenges — primarily high variability, especially for solar and wind. This paper highlights the challenges and opportunities in grid integration of large-scale solar photovoltaic...
This paper presents new findings on phenomena contributing to flicker and voltage variations caused by grid-connected photovoltaic (PV) inverters. The voltage variations caused by two different 6 kW single-phase grid-connected PV inverters were studied during climatic variations by varying their grid-coupling impedance. Two different methods for characterizing the PV-plant induced voltage variations...
The paper describes voltage dips detection method in cases of grid-tie inverter systems. A newly developed harmonic estimation algorithm, Reduced FFT (RFFT), has been applied. The grid-tie inverter system has been modelled and simulated in the Matlab/SimPowerSystems environment. Laboratory experiment was carried out with dSPACE control hardware. The voltage dips were produced by grid emulator. For...
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