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Multi-level transformerless inverters are widely used in grid-tied PV systems since they characterized by higher efficiency and lower cost. In this context, new topologies, modulation, and control schemes were presented to solve problems of a common-mode voltage and leakage current. This work proposes a transformerless five-level inverter with zero leakage current and ability to reduce the harmonic output content for a grid-tied single-phase PV system. The neutral of the grid links to a common on which the negative and the positive terminals of the DC-link are connected via parasitic capacitors that can eliminate the leakage current. The proposed topology, with its inherent circuit structure, leads to boost the overall efficiency. Simulation and experimental results show almost zero leakage current and a high-quality output when maintaining balanced capacitor voltages on the DC-link input. The experimental results show 1.07% THD and 96.3 % maximum efficiency when injecting a power of 1.1 kW that verify the performance of the proposed inverter with PV sources. INDEX TERMS IGBT inverters, transformerless grid-connected photovoltaic inverter, solar PV.

Purpose Several countries have been using internet of things (IoT) devices in the healthcare sector to combat COVID-19. Therefore, this study aims to examine the doctors’ intentions to use IoT healthcare devices in Iraq during the COVID-19 pandemic. Design/methodology/approach This study proposed a model based on the integration of the innovation diffusion theory (IDT). This included compatibility, trialability and image and a set of exogenous factors such as computer self-efficacy, privacy and cost into the technology acceptance model comprising perceived ease of use, perceived usefulness, attitude and behavioral intention to use. Findings The findings revealed that compatibility and image of the IDT factors, have a significant impact on the perceived ease of use, perceived usefulness and behavioral intention, but trialability has a significant impact on perceived ease of use, perceived usefulness and insignificant impact on behavioral intention. Additionally, external factors such as privacy and cost significantly impacted doctors’ behavioral intention to use. Moreover, doctors’ computer self-efficacy significantly influenced the perceived ease of use, perceived usefulness and behavioral intention to use. Furthermore, perceived ease of use has a significant impact on perceived usefulness and attitude, perceived usefulness has a significant impact on attitude, which, in turn, significantly impacting doctors' behavior toward an intention to use. Research limitations/implications The limitations of the present study are the retractions of the number of participants and the lack of qualitative methods. Originality/value The finding of this study could benefit researchers, doctors and policymakers in the adaption of IoT technologies in the health sectors, especially in developing counties.

In the electric power distribution system, power electronics technologies associated with renewable energy systems (RES) and smart grids have gained growing interest. The power electronics devices are used to convert, control, or transfer electric power from RES to the power grids. However, the continuous increase in switching frequencies resulting from these power electronics technologies has led to the emergence of new emissions in the range of 2-150 kHz, outside the classical frequency range for power quality. These emissions are known worldwide as supraharmonics (SH).These emissions negatively affect the power quality of electrical distribution systems and reduce their efficiency and lifetime. Thus, the supraharmonics emissions have been investigated in the literature, and several methods were developed focusing on identifying, measuring, and setting new standards to mitigate the impact of these emissions on the power quality. Although these individual studies have been well documented, a comparative overview of its identifications, current standards, and measurement techniques had not been described so far. Therefore, this study extensively reviews the related techniques and standards for identifying, measuring, and mitigating SH emissions. Moreover, the current research gap in this important field is highlighted, and an illustration on how this problem was tackled in the past few years is presented. Additionally, the SH characteristics alongside with insights into the mitigations and measurements are highlighted and analyzed accordingly. Finally, some important recommendations to mitigate SH emissions are suggested. This review will hopefully strengthen the efforts toward the development of SH domain by providing the necessary groundwork for further mitigations, standards, and measuring techniques improvement. INDEX TERMS Grid integration; harmonics emissions; high frequency; power quality; renewable energy sources; supraharmonics.

Electric vehicles (EVs) could be used to address the issues of environmental pollution and the depletion of non-renewable energy resources. EVs, which are energized by a battery storage system, are becoming attractive because they keep the environment clean. Furthermore, the cost of EVs is becoming cheaper. Thus, EVs will become a significant load on utility distribution system in the future. EV chargers play a significant role in the expansion of EVs. The input current of an EV charger with a high total harmonic distortion (THD) and a high ripple distortion of the output voltage can impact battery life and battery charging time. Furthermore, the high cost and large size of the chargers are considered other issues in EV development. This work presents the complete design process of a universal EV charger with a special focus on its control algorithms. In this regard, a novel control algorithm based on the integration of voltage-oriented control (VOC) and the sinusoidal pulse-width modulation (SPWM) technique is proposed to ensure effective Levels 1, 2, and 3 battery charging. A simulation of the universal EV charger was conducted and assessed in MATLAB-Simulink. Moreover, a laboratory prototype was constructed with a TMS320F28335 digital signal processor (DSP) programmed as the controller to validate its operation and performance. The findings show that the proposed charger is able to provide a controllable and constant charging voltage for a variety of EVs, with an input current of low total harmonic distortion (THD) and an almost unity power factor.

The mission of the power system operator has become more complicated than before due to increasing load demand, which causes power systems to operate near their security limits. The deregulation of electricity markets, which requires independent system operation driven by economic considerations, is still an essential requirement of modern power systems. This study presents an enhanced model of developed adaptive artificial neural network (AANN) technique for security enhancement of Malaysian power grids, inclusive of a remedial action (generation redispatch/load shedding) at any scale of system operation. Automatic data knowledge generation systems for AANN inputs and data selection and extraction methods are developed. Results show that the proposed AANN can provide the required amount of generation redispatch and load shedding accurately and promptly for computing large sample data.INDEX TERMS Security assessment, artificial neural network (ANN), backpropagation, remedial action, contingency analysis.

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This paper presents the enhancements performed on the adaptive linear neuron (ADALINE) technique so that it can be applied for active power filtering purposes in a three-phase four-wire system. In the context of active power filtering, the ADALINE technique which was initially developed for a single-phase two-wire system has been further expanded to suit three-phase three-wire system. For both systems, ADALINE techniques have been reported to be effective even when the grid voltage is distorted and/or unbalanced. However, further works that study the possibility to apply ADALINE technique in a three-phase four-wire system which invariably carries unbalanced loads, are rather limited. Hence, in this work, a control algorithm (named as enhanced-ADALINE) which combines the strength of highly selective filter (HSF), ADALINE concept and averaging function is proposed, to manage harmonics mitigation by shunt active power filter (SAPF) under non-ideal grid and unbalanced load scenarios. MATLAB-Simulink software is utilized to conduct an exhaustive simulation study which includes circuit connection of SAPF in a three-phase four-wire system, design of control algorithms, and performance assessments. Benchmarking with the existing algorithm is performed to examine the benefits of using the proposed algorithm. From the analysis, simulation findings are presented and thoroughly discussed to verify design concept, capability, and relevance of the proposed algorithm.