Increased penetration of distributed energy resources into conventional power systems increases control challenges. These can be suitably met by microgrids. This paper examines the architecture of microgrids and reviews their classifications and the literatures discussing their control objectives during islanded mode. It finds the use of microgrids enhancing the conventional power system's grid smartness. It also summarizes microgrid control objectives and their most common problems and solutions.
Photovoltaic (PV) sources have recently become one of the most mature technologies. With the increasing penetration level and the integration of a PV system into the grid, the stability and reliability of the power networks have been serious concerns. Thus, grid codes are being released by grid operators for low voltage networks under grid faults. Consequently, the Low Voltage Ride Through (LVRT) capability of the grid connected PV system became the most important issue related to grid codes, i.e., more reactive power is injected into the grid during voltage disturbances. In this paper, a comprehensive review of reactive power control strategies for the three-phase PV system has been analyzed to support the grid during voltage sags by providing LVRT capability. The control techniques have been classified into three main categories: Fixed power factor, constant active power control, and constant reactive power control. The results illustrate that the stability of the system is improved when two control techniques are simultaneously implemented. This paper concludes that further research must be carried on LVRT control techniques for the reactive power injection during unbalanced voltage sags.
The grid connected photovoltaic (PV) power plants (PVPPs) are booming nowadays. The main problem facing the PV power plants deployment is the intermittency which leads to instability of the grid. In order to stabilize the grid, either energy storage device -mainly batteries -or a power curtailment technique can be used. The additional cost on utilizing batteries make it not preferred solution, because it leads to a drop in the return on investment (ROI) of the project. A good alternative, is using a customized load (such as; cryptocurrency-based loads) which consumes the surplus energy. This paper investigating the usage of a customized load -cryptocurrency mining rig -to create an added value for the owner of the plant and increase the ROI of the project. These devices are widely used to perform the required calculations for validating the transactions on the network of the Blockchain. A comparison between the ROI of the mining rig and the battery have been conducted in this study. Based on this study the mining rig has superior ROI of 7.7% -in the case with the lowest ROI -compared to 4.5% for battery. Moreover, an improved controlling strategy is developed to combine both the battery and mining rig in the same system. The developed strategy is able to keep the profitability as high as possible during the fluctuation of the mining network.
Because of the effects of climate change, a sustainable transportation system based on renewable energy resources needs to be developed to improve the quality of life. In this study, three sustainable transportation designs and an on-grid power plant design using photovoltaic (PV) panels were analyzed for their feasibility as an alternative to diesel-powered tourist boats. Various financial and technical aspects were considered, such as the local irradiation, energy yield, and system energy loss. As a case study, a solaraided boat was considered, where an off-grid rooftop PV system with 9.8 kWh batteries was installed to meet the energy requirements for internal services and reduce diesel usage. The solar-aided boat was demonstrated to be an economical solution, where the PV system reduced the diesel consumption of the boat by 15% and produced an annual energy output of 5540 kWh. For fully electric solar boats, simulation results showed that a 60 kWh battery system covers the initial investment within 9 years, while a solar boat with 120 kWh a battery system covers it in 13 years. A 300 kW on-grid PV plant was analyzed for its ability to meet the energy demands of an entire tourist boat fleet, and the plant was estimated to reduce CO 2 emissions by 330 tons each year. These findings show that various off-grid rooftop PV systems can be adapted for sustainable transportation while reducing the operating costs of the boat. This study also promotes the transition of boats to cleaner and more sustainable energy sources.
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