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Nigeria’s energy transition plan is hinged on increasing the energy mix from renewable energy sources. An understanding of where the potentials of these renewable energy sources lie is very crucial to enhance quality and timely policy formulations, interventions and proper decision making. This paper aims at providing a holistic assessment of the potentials of key renewable energy resources; solar, wind, biomass and small hydro in Nigeria using ArcGIS; a geospatial analytical platform that provide data and visualizations of these potentials across the country. This paper focuses on the Inverse Distance weighting methodology which overlays various map shapefiles and spreadsheets containing relevant data such as; waterlines and water areas, road and rail networks, crop production, longitude and latitude, wind speeds, solar irradiation, elevation and other relevant map data, shape files for all the Nigerian states and local governments. These data are geo-processed to align the results to the exact locations as provided by their geographical positions stem coordinates. These interpolation results are further reclassed within standard limits for the various output parameters such as crops, forest areas, built-up areas, water bodies, shrubs/grasslands, barren lands and waterbodies to reveal suitability areas for siting the various renewable energy power generating plants.

Life Cycle Assessment (LCA) method is employed to study and mitigate negative environmental impacts using various approaches via OpenLCA software. This paper investigates the LCA of green hydrogen gas production from produced water in Oman, using the Activated Sludge Method (ASM) and Fluidized-Bed Bioreactor (FBB), as treatment technologies. Different scenarios were considered, utilizing the ReCiPe midpoint impact method over 100 years, to evaluate global warming potential (GWP100), fossil depletion potential (FDP), and water depletion (WDP). The objective is to compare and evaluate the sustainability of Dark Fermentation (DF) and Electrolysis methods for hydrogen gas production from both treatment technologies to achieve Oman's Vision 2040. The DF method involves utilizing sludge from both primary and secondary treatment stages, while the Electrolysis method uses the tertiary treatment stage. Results show that using 50 % (15,000 m³/day) of the flow for hydrogen production, the DF yields 60,000 kg of H2/day, while the electrolysis method produces 833,333 kg of H2/day. This difference arises because the DF method depends on sludge production, impacting hydrogen gas production, whereas, the electrolysis method relies entirely on treated water. Both processes significantly impact GWP100. Incorporating solar power for ASM and FBB, as a green energy source, reduces CO2 emissions by 7560.28 kg CO2-eq for DF and 8245.18 kg CO2-eq for electrolysis. This study provides a novelty application, which contributes to advancing sustainability practices through evaluating the environmental impacts of using produced water for green hydrogen production in waste-to-energy and advocates for energy policy making regarding recent climate change commitments.

This paper presents a comparative environmental impact assessment considering different power generation strategies in Oman. The Life-Cycle Assessment (LCA) methodology, and the OpenLCA tool, were employed in carrying out comprehensive analysis, and evaluation of the various environmental aspects in filling the research gap, by replacing conventional diesel generators with natural gas alternatives in Oman. The obtained results indicate that utilizing natural gas significantly reduces environmental impacts, including a decrease in global warming potential to 2.27 million kg CO2 eq, fossil fuel depletion to 34.5 million kg oil-eq, and ozone depletion to 0.13 kg CFC-11 eq. This study would help in policy decision-making to support a potential shift in power generation system, transitioning from the current use of diesel generator sets to flared produced Natural Gas across crude oil processing plants. Thus, mitigating operational cost, and improving efficiencies, for sustainable developments. Another salient part of this study is the implementation of more sustainable energy practices that supports the broader application of LCA in evaluating industrial environmental impacts. Furthermore, the results obtained in this work are in line with recent global climate change commitments and Oman's Vision 2040, in achieving cleaner energy sources to minimize environmental harm in the oil and gas sector.

Solar mini-grids are a cost-effective and efficient method of improving energy access in sub-Saharan Africa, particularly in low-income communities. However, conventional battery storage systems have reduced the affordability of solar mini-grid-generated electricity, necessitating the development of alternative energy storage systems such as pumped hydro storage to replace lithium-ion batteries. This paper introduces a model for an SMS-based fluid parameter monitoring system to provide visibility of reservoir conditions during peak and off-peak periods. The model uses hardware such as voltage regulators, sensors, microcontrollers, and C- programming language software. Sensors monitor various parameters in the reservoir and penstock, transmitting signals to a microcontroller for analysis. The results are relayed to a display unit and personnel's mobile phones for alert notifications, ensuring precise and accurate reporting. Simulation results show the reliability of the design to monitor water levels, water temperature, flow rate, and transmission through SMS to mobile devices for timely reporting. The paper recommends the development and commercialization of this model for larger applications, such as monitoring dams for irrigation and power generation.

This paper focuses on the prospects of small hydropower plants (SHP) in Nigeria and utilizes ArcGIS software for analyzing the country’s hydropower energy potential. The analysis conducted using ArcGIS reveals the significant SHP potential in various states across Nigeria. By overlaying water areas and waterline data on maps, potential sites for SHP are identified, particularly in states such as Borno, Niger, Edo, Anambra, and Jigawa. Further analysis was done using data for water lines in Nigeria converted into shaped files for the six geopolitical zones of Nigeria, with the various states and local government areas, to provide expanded views for different possible schemes for SHP. Data set were built up for the different geopolitical zones and statistical analyses were done for SHP potentials. Interpolations were performed using Inverse Distance Weighting (IDW) tool on ArcGIS to show areas ideally suitable to site dam schemes for hydropower production and other schemes that require less water storage for small hydropower production. The strengths of each state in the various zones with regard to water inlands and lands subject to inundation were also identified. Some major challenges and opportunities in using ArcGIS in assessing small hydropower schemes in Nigeria, were also highlighted.

Recently, the management of water and wastewater is gaining attention worldwide as a way of conserving the natural resources on the planet. The traditional wastewater treatment in Oman is such that the treated effluent produced is only reused for unfeasible purposes such as landscape irrigation, cooling, or disposed of in the sea. Introducing more progressive reuse applications can result in achieving a circular economy by considering treated effluent as a source of producing new products. Accordingly, wastewater treatment plants can provide feedstock for green hydrogen production processes. The involvement of the wastewater industry in the green pathway of production scores major points in achieving decarbonization. In this paper, the technical and economic feasibility of green hydrogen production in Oman was carried out using a new technique that would help explore the benefits of the treated effluent from wastewater treatment in Oman. The feasibility study was conducted using the Al Ansab sewage treatment plant in the governate of Muscat in Wilayat (region), Bousher. The results have shown that the revenue from Al Ansab STP in a conventional case is 7.02 million OMR/year, while sustainable alternatives to produce hydrogen from the Proton Exchange Membrane (PEM) electrolyzer system for two cases with capacities of 1,500 kg H2/day and 50,000 kg H2/day, would produce revenue of 8.30 million OMR/year and 49.73 million OMR/year, respectively.

The wind energy conversion technology of a Permanent Magnet Synchronous Generator (PMSG) is very promising in renewable power generation. However, the performance of the grid-connected PMSGs is greatly affected by grid disturbances because their stator windings are interfaced with the grid directly. There are different Fault Current Limiter (FCL) topologies that are capable of improving the Fault Ride Through (FRT) capability of PMSG wind turbines during short circuit faults. This study investigates three types of FCLs connected to the grid side of the PMSG wind turbine: Series Dynamic Braking Resistor (SDBR), traditional Bridge Fault Current Limiter (BFCL), and Capacitive Bridge Fault Current Limiter (CBFCL). Complete modeling of FCLs was derived in order to understand their behaviors accurately during normal conditions and fault periods. The performance of the three FCLs in the PMSG wind turbine was analyzed and compared using a severe three-phase to ground fault at the terminal of the PMSG wind turbine in Power System Computer Design and Electromagnetic Transient Including DC (PSCAD/EMTDC) platform. The same conditions of operation were used in investigating the various FCL strategies in the PMSG wind turbine considered in this study during grid fault for effective comparison.

Solar Photovoltaic (PV) offers hope toward environmental sustainability in terms of carbon and global heat reduction. The harvested energy from solar PV depends on the solar radiation, temperature of the cells, and the voltage generated in the PV modules. With the recent proliferation of solar PV projects in Oman, it is imperative to carry out new studies on the causes and effects of failures of these grid connected PVs, for effective and reliable performance. This study serves as a prototype to evaluate the performance of solar PV installations in Oman, considering the possible failures that may occur. These failures could lead to poor performance of the solar PV systems during operation. The performance analysis of a 6.2 MW grid-connected solar photovoltaic system in Muscat car parking, Oman is presented in this paper. The electrical parameters, and data analysis of the PV system were evaluated by monitoring the voltage, frequency, power factor, and total output power variables. The analysis of the PV performance was based on three internal dynamic failures; dust accumulation, inverter malfunction, and faulty protection schemes. When the solar PV cells were exposed to high percentage of contamination and dust, the plant performance dropped sharply to lower power generation by 43.5%. Furthermore, Inverters failure data analysis show that the average power generation degraded by 34%, and the average power generation degradation of 1% in the same period due to protection schemes failure. The results demonstrated that dust accumulation and inverter malfunction are the two major shortcomings that could lead to low power efficiency of solar PVs during operation.

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, there has been a rise in the integration of renewable energy sources into power grids. As a result of this, there is a need to carry out new studies in order to understand the dynamics of power grids during disturbances that is mainly caused by the stochastic nature of wind energy. The operation of modern power grids that are tied to wind farms follows a stipulated grid requirement or grid codes, considering the allowable threshold frequency variation during grid dynamics. This paper presents a comparative study of two frequency control schemes considering grid frequency stability using two frequency control topologies. A novel dynamic flywheel scheme with a doubly fed induction generator (DFIG) variable-speed wind turbine with the coordinated control of excess kinetic energy and mechanical torque during operation was the first scheme, and a control strategy of an energy capacitor system (ECS) with a squirrel cage induction generator fixed-speed wind turbine (FSWT) was the second scheme. The salient part of this study was that the DFIG maximum point power tracking for effective smoothing of the output of the wind generator in the first scheme was designed based on the control strategy of its reference power to achieve smoothing of the wind power at the terminals of the wind generator. The model system employed in this work was a wind farm that is tied to a conventional power grid made of steam and hydro synchronous turbines. For an effective and fair comparison of results, the same natural wind speed was used in PSCAD/EMTDC for both schemes. When no control, Scheme 1, and Scheme 2 were implemented, the frequency dips were 47.20, 49.99, and 49.99 Hz with overshoots of 50.500, 50.005, and 50.001 Hz and recovery times of over 600.00, 0.01, 0.01 s, respectively, for the frequency variable.

The privatization exercise that led to the creation of 11 distribution companies (Discos) is yet to yield the result of meeting the electricity supply needs of Nigeria. It is in realization of this fact that the Federal Government of Nigeria recently made different proposals and regulations to increase efficiency, availability, and competitiveness within the power industry. This article establishes a technical gain ratio to measure the impact of scaling up smart metering on the aggregated technical commercial and collection (ATC&C) losses. The ATC&C loss is the difference between the amount of electricity received by a distribution company from the transmission company and the amount of electricity for which it invoices its customers plus the adjusted collections loss. To achieve this objective, reviews of historical data of the Discos ATC&C losses and customers’ metering records as published by the Nigerian Electricity Regulatory Commission (NERC) for 2015, 2016, 2017, 2018, and 2020 were carried out. In addition, efforts were made to mathematically model the relationship between % metering and % ATC&C losses as this was the framework to help carry out effective forecasts and analyses of the study in order to show the impact level of the strategy employed. One of the salient technical contributions of this article was that it established that for every 1% increase in metering installation, there is a proportionate 0.8% decrease in ATC&C losses, provided all other factors responsible for technical and commercial losses remain constant. Consequently, improved ATC&C loss reduction would be achieved if Discos adopt a combination of other strategies that would ensure reduction in technical and commercial losses in addition to aggressive deployment of meter assets. However, in practice, factors causing technical and commercial losses are never constant as system components depreciate/burn out with time, energy theft, and pilferage, and meter tamper/bypass is on the increase daily; meter deployment is not aggressive enough to match utility customers’ growth. Hence, the adoption of combined modern strategies in addition to aggressive metering in tandem with customers’ growth has to be employed by Discos in a deliberate attempt to reduce ATC&C losses.

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.

The recently stipulated grid codes require wind generators to re-initiate normal power production after grid voltage sag. This paper presents a comparative performance of two commonly employed variable speed wind turbines in today’s electricity market, the doubly fed induction generator (DFIG) and the permanent magnet synchronous generator (PMSG) wind turbines. The evaluation of both wind turbines was performed for weak, normal and strong grids, considering the same machine ratings of the wind turbines. Because of the critical situations of the wind turbines during faulty conditions in the weak grids, an analysis was done considering the use of effective series dynamic braking resistor (SDBR) for both wind turbines. The grid voltage variable was employed as the signal for switching the SDBR in both wind turbines during transient state. Additionally, an overvoltage protection system was considered for both wind turbines using the DC chopper in the DC-link excitation circuitry of both wind turbines. Furthermore, a combination of the SDBR over-voltage protection scheme (OVPS) was employed in both wind turbines at weak grid condition in order to improve the performance of the variable speed wind turbines and keep the operation of the power converters within their permissible limits. Furthermore, the performance of the DFIG and PMSG wind turbines in weak grids were further investigated, considering the combination of 75% and 50% effectively sized SDBR and OVPS. It was observed that, even with a 50% reduction in SDBR or OVPS, the performance of both wind turbines is still satisfactory with faulty conditions. Therefore, it is recommended to use a combination of the SDBR and OVPS with DFIG- or PMSG-based variable speed wind turbines to achieve a superior fault ride through performance, especially in weak grids. The system performance was evaluated using the power system computer design and electromagnetic transient including DC (PSCAD/EMTDC) platform.

This article presents an overview of the transmission system and protection schemes employed in the national power grid of Oman. The technical design requirements considering the percentage of allowable limits for the different transmission voltage levels in the power grid of Oman were considered based on the electrical standards and grid codes of Oman. Also, the protection and fault requirements based on relay settings and backup protection were some of the factors considered in this study. More so, the power flow, peak, and off-peak voltage profiles of the main interconnection and Dhofar transmission systems were analyzed in detail, considering projections for 2021 and 2025, respectively, for effective energy management and smart grid operations. The current protection equipment of the power grid of Oman was evaluated, and some improvement schemes were proposed considering the implementation of the new technology for smart grid operation. The continuous investment in the transmission system of the Oman power grid and the use of updated protection technology would lead to the enhancement of the performance of the Oman transmission system to reach a high-level power transmission availability.

Currently, there is a global challenge of water scarcity due to climate change, rising temperatures, and other factors. One way to address this growing global challenge is by implementing technology to treat polluted water by reusing it in areas such as irrigation, cooling, and energy production, based on bio-hydrogen gas. Hydrogen gas can be produced by several methods, including dark fermentation. In this study, hydrogen gas was produced by 1L of sludge and Treated Effluent (TE) with several methods, using a reactor with a volume of 0.96 H2 L/L media. The Life-Cycle Impact Assessment (LCIA) process was used to study resource depletion, the ecosystem, and human impacts, and efforts were made to reduce the negative impacts by implementing several solutions. In this study, OpenLCA software was used as a tool for calculating the impacts, along with the ecoinvent database. Further analysis was carried out by comparing the LCIA with and without the use of solar energy. The results show that implementing hydrogen gas production with a solar energy system will help to obtain the best solution and reduce the carbon footprint, with 1.12 × 104 kg CO2 equivalent and a water depletion of 2.83 × 104 m3.

Hydropower technology is a simple and renewable form of energy that involves the conversion of potential energy due to head and mass flow rate of water into kinetic energy that drives a water turbine connected to a generator. In this paper, the potential of hydropower in the Sultanate of Oman is studied, considering Wadi Dayqah Dam in Quriyat. The following variables of the dam were used in evaluating its potential for electricity generation for the year 2010 through 2018: the amount of water flowing in and out of the dam and the amount of water available in the dam at the beginning and end of the considered years. A recommendation was made for the type of hydro turbine for maximum power extraction from the dam, based on the available water head and flow rate, considering the standard characteristic selection envelope for hydro turbines. Power generation from the dam could be affected as a result of the decline in reservoir water level, the continuous release of water for irrigation purposes, fear of the aftermath of a cyclone, lack of rains for consecutive years, and high evaporation. However, the occurrence of a cyclone increases the reservoir water level of the dam for more power generation. Some long-term scenarios for effective operation of the dam considering water availability and management were discussed. In addition, some ways of mitigating water loss from the reservoir of the dam through evaporation were proposed.

This study investigates the transient performance of two variable speed wind turbines (VSWTs), namely doubly fed induction generator (DFIG) and the permanent magnet synchronous generator (PMSG), that are widely employed in wind energy conversion, considering their machine parameters. The machine parameters of both wind turbines were changed considering different scenarios, while keeping other parameters constant, to study the behavior of the wind generators. This study was carried out using the same operating conditions of rated wind speed, based on the characteristics of both wind turbine technologies. The wind turbines were subjected to a severe three phase to ground bolted fault to test the robustness of their controllers during grid fault conditions. Efforts were made to carry out an extensive comparative study to investigate the machine parameters that have more influence on the stability of the different wind turbines considered in this study. Simulations were carried out using power system computer-aided design and electromagnetic transient including DC (PSCAD/EMTDC). Effective machine parameter selection could help solve fault ride-through (FRT) problems cost-effectively for both VSWTs, without considering the external circuitry of and changing the original architecture of the wind turbines.

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 control of grid frequency in power systems due to the penetration of wind turbines is vital to maintaining the stability of power grids, based on recent grid requirements. In this paper, the dynamic behaviour of a wind farm connected to an existing grid is presented. The existing grid is made up of steam turbines, while the wind farm is based on squirrel cage induction generators. An energy capacitor system is used to stabilize the wind farm during periods of wind speed change. Loads with various capacities were connected to the grid to test the robustness of the controllers of the energy capacitor system employed. Furthermore, the effect of varying the time constant of the in-built DC-DC chopper of the energy capacitor system was investigated, considering load participation in the grid. One of the targets of this paper is the stabilization of the grid frequency of the network, despite the load capacity and the nature of the wind speed in the wind farm. The system performance was evaluated using Power System Computer Design and Electromagnetic Transient Including DC (PSCAD/EMTDC). The same conditions of operation were used to investigate the various scenarios considered in this study, to ensure an effective comparison. The natural wind speed employed was the same for all the considered scenarios. The presented results show that small load capacity with a high value low pass filter time constant, provided better response for the grid frequency and the entire variables of the power network.

The technology of variable speed wind turbines is very promising in renewable power generation. It is imperative for wind turbines to gain control after grid disturbances and contribute to the stability of power grids as part of the requirements of grid codes set by grid operators in operating wind farms. Fault current limiters (FCLs) are capable of augmenting the performance of wind turbines during grid disturbances. In this article, the augmentation of the Doubly Fed Induction Generator (DFIG) and the Permanent Magnet Synchronous Generator (PMSG) wind turbines, which are the two most popular variable speed wind turbines, is presented. The evaluation of both wind turbines was performed considering the Series Dynamic Braking Resistor (SDBR), Bridge Fault Current Limiter (BFCL) and the Capacitive Bridge Fault Current Limiter (CBFCL). The modeling of the FCLs in the wind turbines was derived for steady state and grid disturbances so that their dynamic behavior could be understood. The grid voltage variable was employed as the signal for switching the FCLs in both wind turbines during grid disturbances. Moreover, a scenario with no control using the FCLs was also carried out for both wind turbines. The performance of the FCLs in both wind turbines was analyzed and compared using a severe three-phase to ground fault at their terminals. For effective comparison, the same conditions of operation were used in investigating the performance of the FCLs control strategies in both wind turbines during grid disturbances. The study was conducted using Power System Computer-Aided Design and Electromagnetic Transient including DC (PSCAD/EMTDC) environment.

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.

In wind energy applications, voltage source converters are employed to achieve energy conservation. Recently, multilevel converters have been showing promising advantages compared to the traditional 2-level converter scheme, due to the fact that they can overcome certain limitations during transient conditions. This paper investigates the transient performance of variable DFIG-based speed wind turbines taking into account different scheme configurations of the power converter system. The schemes investigated are a 2-level six step IGBT inverter, a parallel interleaved 2-level six step IGBT inverter, and a 3-level IGBT inverter. All schemes were compared during severe three-phase to ground fault at the terminal of the DFIG wind turbine using the conventional Phase Lock Loop (PLL) and a DC-chopper protection. A coordinated approach of improving the performance of all the converter schemes with series dynamic braking resistor (SDBR) was analyzed. Investigation of the best location for the SDBR in the DFIG architecture considering the best switching signal was also carried out. Furthermore, a new control strategy of PLL for the DFIG system was proposed in conjunction with the SDBR scheme for the converter systems. Simulations were carried out in Power System Computer Aided Design and Electromagnetic Transient Including DC (PSCAD/EMTDC). The results show that the proposed PLL and SDBR hybrid scheme in the various inverter topologies considered in the study can enhance the performance of the wind generator variables during severe three-phase to ground fault. This is because the proposed hybrid scheme could help to boost the capability of the current and recovery of the wind generator after post-fault scenarios. Also, the voltage source converter leg switched output voltage would be enhanced to maximum change in common mode voltage by the inverter schemes’ modulation of the space vector using the proposed strategy.

Nigeria is purely an agrarian nation and the people depend on agriculture for survival. One of the missing links to wealth creation in Nigeria is lack of economic exploitation of abundant agricultural wastes. Instead of wealth creation, rice husk has become a serious threat to the environment. The unutilized rice husks in rice mills in Nigeria generate millions of tons of C02 when burnt. This increases environmental degradation and deaths associated with respiratory diseases. The sustainable use of this rice husk for bioenergy applications such as electricity generation at low cost, to mitigate greenhouse gas emissions is imperative. In this paper, an off-grid gasification power supply option for Adani, in Uzo-Uwani Local Government Area of Enugu state, of eastern Nigeria is presented. A detailed load assessment and availability of rice husk for power generation in the study area was conducted. This information was used to design the gasification system. The gasification system was designed based on the mass flow rate of producer gas required to power the gas engine at full load. The gasifier was designed downdraft with air and steam as the oxidizing agent, in order to maintain uniform temperature in the oxidation and reduction zones. Furthermore, techno-economic analysis approach was used to determine the economic viability of the designed power system considered in this study. The estimated total load demand of the study area is 850.054kW. The estimated total daily, monthly and yearly energy demands of the study area are: 8,991 ​kWh, 269,736.42 ​kWh and 3,236,837.04 ​kWh. The annual availability of rice husk in the study area is 3,636t/y and it has potential of 1.52MW power generation with daily, monthly and yearly energy generation of: 36.48 ​MWh, 1,094.4 ​MWh and 13,132.8 ​MWh. This potential of electricity generation has power station capacity of 1.9 MVA, which is approximately equal to 2 MVA. The Levelized Cost of Electricity of the designed power system is 3.6 Naira/kWh, which is cheaper than 30.93 Naira/kWh tariff bill by Enugu Electricity Distribution Company to its R2S customers. Based on the proposed rice husk gasification system, a community could generate power to meet their electricity demand in most economical way, thereby reducing emission, waste and saving cost translating to sustainable development.