Investigation of the Magnetic Response of a Nanocrystalline High-Frequency Magnetic Link With Multi-Input Excitations

© 2019 IEEE. With the technological advancement of magnetic materials and semiconductor devices, the use of high-frequency magnetic link made of high-saturation induction and low specific core loss nanocrystalline alloy has been gaining popularity to replace the common dc link or ac link specially in integrating multiple renewable sources to the grid. The magnetic integration of multiple renewable sources through a common magnetic link has a number of advantages including galvanic isolation compared with the common dc or ac link. However, the magnetic response of the common magnetic link under multi-input excitations highly affects the energy conversion efficiency. To the best of the authors' knowledge, the magnetic response of an advanced magnetic-material-based magnetic link under multi-input excitations has not been well investigated in the literature. In this paper, a systematic investigation is carried out to interconnect multiple sources through a common magnetic link. The magnetic response and the procedure used in the investigation are also presented and discussed in this paper

A Modified Carrier-Based Advanced Modulation Technique for Improved Switching Performance of Magnetic-Linked Medium-Voltage Converters

© 1972-2012 IEEE. The high-frequency magnetic link is gaining popularity due to its lightweight, small volume, and inherent voltage balancing capability. Those features can simplify the utilization of a multilevel converter (MLC) for the integration of renewable energy sources to the grid with compact size and exert economic feasibility. The modulation and control of the MLC are crucial issues, especially for grid-connected applications. To support the grid, the converter may need to operate in an overmodulation (OVM) region for short periods depending upon the loading conditions. This OVM operation of the converter causes increased harmonic losses and adverse effects on the overall system efficiency. On top of that, the size and cost of filtering circuitry become critical to eliminate the unwanted harmonics. In this regard, a modified OVM scheme with phase-disposed carriers for a grid-connected high-frequency magnetic-link-based cascaded H-bridge (CHB) MLC is proposed for the suppression of harmonics and the reduction of converter loss. Furthermore, with the proposed OVM technique, the voltage gain with the modulation index can be increased up to the range which is unlikely to be achieved using the classical ones. Extensive simulations are carried out with a 2.24 MVA permanent magnet synchronous generator based wind energy conversion system, which is connected to the 11 kV ac grid through a high-frequency magnetic-link and a five-level CHB MLC. A scaled down laboratory prototype is implemented to validate the performance of the converter

Role of optimization algorithms based fuzzy controller in achieving induction motor performance enhancement.

Three-phase induction motors (TIMs) are widely used for machines in industrial operations. As an accurate and robust controller, fuzzy logic controller (FLC) is crucial in designing TIMs control systems. The performance of FLC highly depends on the membership function (MF) variables, which are evaluated by heuristic approaches, leading to a high processing time. To address these issues, optimisation algorithms for TIMs have received increasing interest among researchers and industrialists. Here, we present an advanced and efficient quantum-inspired lightning search algorithm (QLSA) to avoid exhaustive conventional heuristic procedures when obtaining MFs. The accuracy of the QLSA based FLC (QLSAF) speed control is superior to other controllers in terms of transient response, damping capability and minimisation of statistical errors under diverse speeds and loads. The performance of the proposed QLSAF speed controller is validated through experiments. Test results under different conditions show consistent speed responses and stator currents with the simulation results

Utilization of Renewable Energy for Power Sector in Yemen: Current Status and Potential Capabilities

A severe energy crisis has plagued Yemen for decades, and most of the population lack access to electricity. This has harmed the country’s economic, social, and industrial growth. Yemen generates electricity mainly from fossil fuels, despite having a high potential for renewable energy. Unfortunately, the situation has recently been compounded by the country’s continuing war, which has been ongoing since early 2015. It has impacted the country’s energy infrastructure negatively, resulting in power outages. Therefore, this paper aims to provide an updated perspective on Yemen’s current energy crisis and explain its key issues and potential solutions. Besides, it examines the potential, development, and current state of renewable energy sources, such as solar, wind, geothermal, and biomass. Based on the findings, Yemen is one of the world’s wealthiest countries in terms of sunlight and wind speed, and these two resources are abundant in all regions of the country. In addition, this paper sheds light on the solar energy revolution that has arisen since the war started due to the complete outage of the national electricity. Within a few years, solar energy in Yemen has increased its capacity by 50 times and has recently become the primary source of electricity for most Yemenis. Furthermore, the paper discusses the difficulties and challenges that face the implementation of renewable energy investment projects. Numerous recommendations for potential improvements in Yemen’s widespread use of renewable energy are also provided in this paper. All of the ideas presented in this paper are hoped to increase the efforts to grow renewable energy production in Yemen, thereby solving the issues of energy poverty and reducing environmental effects. The presented analysis can be used as a scientific reference for researchers and industrial companies looking for suitable solutions to advance Yemen’s renewable energy

Impact of renewable energy utilization and artificial intelligence in achieving sustainable development goals

Many countries around the world are planning to reach 100% renewable energy use by 2050. In this context and due to the recent sharp increase in RE utilization in the global energy mix along with its progressive impact on the world energy sector, the evaluation and investigation of its effect on achieving sustainable development goals are not covered sufficiently. Moreover, an assessment of the emerging role of artificial intelligence for renewable energy utilization toward achieving SDGs is conducted. A total of 17 SDGs were divided into three groups, namely, environment, society, and economy, as per the three key pillars of sustainable development. Renewable energy has a positive impact toward achieving 75 targets across all sustainable development goals by using an expert elicitation method-based consensus. However, it may negatively affect the accomplishment of the 27 targets. In addition, artificial intelligence can help renewable energy enable the attainment of 42 out of 169 targets. However, with the current exponential growth of renewable energy share and artificial intelligence development and addressing certain present limitations, this impact may cover additional targets in the future. Nevertheless, recent research foci overlook essential aspects. The exponential growth of renewable energy share and rapid evolution of artificial intelligence need to be accompanied through the requisite regulatory insight and technology regulation to cover additional targets in the future

A modified dc chopper for limiting the fault current and controlling the dc-link voltage to enhance fault ride-through capability of doubly-fed induction-generator-based wind turbine

A simple conventional dc chopper is employed to protect the doubly-fed induction generator (DFIG) from overvoltage; however, it is not capable to keep the transient overcurrent in an acceptable level in stator and rotor sides. Therefore, an effective current-limiting strategy should be incorporated with the dc chopper to improve the fault ride-through capability of the DFIG. In this paper, a modified DC chopper is proposed not only to keep the dc-link voltage in an acceptable range, but also to limit the high-current level in the stator and the rotor sides in a permissible level without incorporating any extra fault-current-limiting strategy. Unlike the conventional dc chopper, in the proposed dc chopper, it is not required to stop rotor-side converter (RSC) switching and employ high-rated-current antiparallel diodes. The proposed modified dc chopper is placed between the dc-link capacitor and the RSC. In the proposed switching strategy of the modified dc chopper, three extra semiconductor switches are included, which are triggered to insert dc chopper resistance either in parallel or series connections with the dc link regarding the dc-link voltage level and the dc-link current level, respectively. Calculation of the dc chopper resistance is discussed. To prove the effectiveness and robustness of the proposed modified dc chopper in terms of both limiting the fault current and controlling the dc-link voltage of the DFIG, symmetrical and asymmetrical grid faults are applied in a power system including the DFIG-based wind turbine modeled in PSCAD/EMTDC so

A modified DC chopper for limiting the fault current and controlling the DC link voltage to enhance ride-through capability of doubly-fed induction generator based wind turbine

According to the grid code requirements, doubly-fed induction generator (DFIG) based wind turbines should remain connected to gird during fault conditions for specific time frame depending voltage sag level. A simple DC chopper is employed in DC-link to protect the DFIG from over-voltage; however it is not capable to keep high transient over-currents in an acceptable level in stator side and rotor side of the DFIG. Therefore, an effective current limiting strategy should be incorporated with the DC chopper to improve fault ride-through (FRT) capability of the DFIG. In this paper, a modified DC-link chopper is proposed to keepboth the DC-link voltage and the high current level in stator and rotor sides in a permissible level without incorporating any extra fault current limiting strategy. Unlike the generalDC chopper configuration, in the proposed DC chopper, it is not required to cease rotor side converter (RSC) switching and employ high rated current antiparallel diodes. The proposed modified DC chopper is placed between the DC-link capacitor and the RSC. In the proposed switching strategy, three extra semiconductor switches are included, which are trigged to insert DC chopper resistance either in parallel or series connections with the DC-link. To prove effectiveness and robustness of the proposed modified DC-link chopper, symmetrical and asymmetrical faults are applied in a power system containing DFIG based wind turbine modelled in PSCAD/EMTDC software. The results are promising in terms of both limiting the fault current and controlling the DC-link voltage of the DFIG