One of the ways of generating electrical power from wind energy is by employing the promising technology of the permanent magnet synchronous generator (PMSG) variable speed wind turbine (VSWT). With the daily increase and integration of wind farms into traditional power grids, it is imperative to carry out transient stability studies of wind generators in wind farms, in order to fulfill the operational grid codes. To solve the transient stability intricacies posed by the stochastic nature of wind energy during transient states or grid faults, this paper presents the enhancement of PMSG wind turbine considering the excitation parameters of the insulated gate bipolar transistors (IGBTs) of the wind generator. The investigation was carried out using the turn on and turn off resistances of the IGBTs of the power converters of the PMSG wind turbine, considering different scenarios, with and without over voltage protection scheme. A severe three-line-to-ground fault was used to test the robustness and rigidity of the controllers of the wind generator during transient state. Furthermore, the results obtained using the PMSG wind turbine were compared to those using the doubly fed induction generator (DFIG) wind turbine. The evaluation of the system performance was done using the power system computer “aided” design and electromagnetic transient including DC (PSCAD/EMTDC) platform. The same conditions of operation were used in investigating the various scenarios considered in this study.

The major aim for achieving the successful synchronization of a wind turbine system to the grid is to mitigate electrical and mechanical stresses on the wind generator. During transient state, the gearbox, shaft, and rotor of the wind generator could be damaged due to mechanical stress. The rotor and stator windings of the wind generator, including its insulation, could be affected. This paper undertakes an extensive analysis of the effects of the excitation parameters of the power converter Insulated Gate Bipolar Transistors (IGBTs), on the transient state performance of the Doubly Fed Induction Generator (DFIG), considering different scenarios. The optimal excitation parameters of IGBTs were used for further analysis of the wind generator, considering a new Phase-Locked-Loop (PLL) scheme. The PLL computes the phase displacement of the grid required to achieve orientation and synchronization control. Consequently, it helps in preventing power system distortion due to stator-grid interphase. This paper proposes a new approach that integrates PLL control strategy and a Series Dynamic Braking Resistor (SDBR) to augment the fault ride through capability of a variable speed wind turbine that is DFIG-based. The SDBR helps the post fault recovery of the wind generator. Simulations were run in Power System Computer Aided Design and Electromagnetic Transient state Including DC (PSCAD/EMTDC) to examine severe fault conditions, and to test the robustness of the controllers employed. The results show that the proposed hybrid control strategy aids the fast recovery of the DFIG wind generator variables during fault conditions.

No abstract

Due to the adverse effect of energy production from traditional fossil fuels, the move toward renewable and sustainable energy has become imperative. The waste disposal sector offers hope toward environmental sustainability and potential to generate strong income for any economy. The region of the Gulf Cooperation Council (GCC) member countries in the Middle East generates the highest quantity of municipal waste per capita, compared to other countries globally. In the GCC region, waste is usually just dumped at different landfill stations. Effective waste management is imperative for environmental protection and sustainable development. This article presents a review of the sustainable waste management strategies in Oman, in line with the United Nations goal on environmental management of waste. The current waste management strategies in Oman were discussed, and various waste-to-energy (WTE) technologies were proposed. These proposed WTE strategies would help in effective waste management in Oman and also in increasing the power grid capability. The salient part of this article is an overview of the ability of using landfill leachate as feedstock to produce clean and green hydrogen gas using different photo-fermentation processes. The production of hydrogen using single photo-fermentation process using landfill leachate alone, with leachate and addition of inoculum such as sewage sludge, and with substrates such as sucrose, glucose, and landfill leachate was investigated by utilizing a batch bioreactor and anaerobic conditions at controlled temperature, different initial pH, and heat treatment temperature range. Furthermore, a prototype model for the optimization of the inoculum size and the substrate was proposed with 2-level factorial design using Design Expert. The data gathering for this study was carried out by investigating different regions in Oman having the lowest and highest waste produce, the average annual waste for the different governorates, and the total amount of waste for five consecutive years (2015–2020), for the various engineered landfills. The cost of managing waste in the different governorates of Oman was presented, considering the average annual waste produced, in various regions of the country for the duration of the study. Furthermore, some challenges and opportunities in carrying out effective waste management in Oman were addressed.

Recently, it has become imperative to find new sustainable and renewable sources of energy, in order to avoid dependence on non-renewable traditional energy resources. This would help to overcome the depleting of natural resources for energy production. Hydrogen gas production using biological processes is one of the most attractive solutions in this regard, due to its high energy content and ecofriendly nature. Production of hydrogen using single photo-fermentation process and landfill leachate as substrate was carried out in this paper, by utilizing batch bio-reactor and anaerobic conditions. The pH value and temperature, play an essential role in a bio-hydrogen production process. Thus, in this study, the pH values considered were 6, 6.5, and 7.2, respectively, at a controlled temperature of 37 ± 1°C. This study investigated various schemes that have the possibility of producing hydrogen using; landfill leachate alone, with leachate and addition of inoculum such as sewage sludge, and with substrate such as sucrose and glucose. All experiments were conducted with and without mixing, for effective comparative study. Heat and pH pretreatment were applied in each experiment with the objectives of decreasing the activities of methane-producing bacteria and enhancing the activities of hydrogen-producing bacteria. The hydraulic retention time used in this study was 48 h, in order to obtain optimal performance of the schemes employed. Analysis of liquid leachate was performed for each experiment, and based on the obtained results, the maximum yield of hydrogen produced was 5,754 ml H2/L, with a medium pH scale of 6.0, fermentation temperature of 37 ± 1°C and constant mixing speed of 100 rpm.