Thanks to smart grids, more intelligent devices may now be integrated into the electric grid, which increases the robustness and resilience of the system. The integration of distributed energy resources is expected to require extensive use of communication systems as well as a variety of interconnected technologies for monitoring, protection, and control. The fault location and diagnosis are essential for the security and well-coordinated operation of these systems since there is also greater risk and different paths for a fault or contingency in the system. Considering smart distribution systems, microgrids, and smart automation substations, a full investigation of fault location in SGs over the distribution domain is still not enough, and this study proposes to analyze the fault location issues and common types of power failures in most of their physical components and communication infrastructure. In addition, we explore several fault location techniques in the smart grid’s distribution sector as well as fault location methods recommended to improve resilience, which will aid readers in choosing methods for their own research. Finally, conclusions are given after discussing the trends in fault location and detection techniques.
This paper reviews and discusses the use of adaptive protections in microgrids. The main goal of the paper is to review the progress made in the last 10 years, to identify the challenges that are still present, and to note the current trends in the use of these protections in microgrids. The analysis is based on applications implemented since 2007, and on a wide bibliographical review of books, theses, patents, scholarly papers, conferences, technical reports, and experts' experiences. The paper includes a comparative table that summarizes the reviewed literature and its findings. The paper is of interest to academics who do research on development and implementation of new robust and reliable protection schemes in microgrids, and to those in the industrial sector, who implement electric microgrids, and who want to understand the impact of their protection schemes.
Extreme weather conditions and natural disasters (ND) are the main causes of power outages in the electric grid. It is necessary to strengthen the electrical power system’s resilience during these catastrophic occurrences, and microgrids may be seen as the best way to achieve this goal. In this paper, two different energy system scenarios were proposed for increasing the resiliency of the electric power system during random outages. In the first scenario, a diesel generator (DG) was used to deliver energy to key loads during grid disruptions, in conjunction with a utility electric grid (UEG) and local electric load (ELL). A grid-connected ad hoc microgrid (MG) with a photovoltaic (PV) system, a battery energy storage (BES) system, and local electric loads made up the second scenario. The PV system and the BES system were used to supply the key loads with electricity during the outage. The major aim of this research was to compare the two resilient-based systems from the perspectives of technology, economics, and the environment. Given that it requires greater resilience than the other loads during severe weather, a hospital load on Indonesia’s Lombok Island was chosen as the critical load. The objective function considers the system’s predefined constraints to reduce the overall net present cost (NPC) and the cost of energy in order to maximize the system resilience (COE). The Optimization of Multiple Energy Resources (HOMER) Grid simulated a 3-day outage in August 2021, and the results demonstrated that the resiliency enhancement for both scenarios was nearly identical. The first scenario resulted in fewer CO2 emissions; however, the second scenario delivered lower operating costs and COE. The simulation’s findings showed that system 1 created an annual emission of 216.902 kg/yr while system 2 only produced an emission of 63.292 kg/yr. This study shows that since RES-based MGs don’t burn fossil fuels to generate power, they are more environmentally friendly resources.
Electrical networks are evolving and taking on more challenges as the inclusion of renewable energy and distributed generation units increase, specially at distribution levels. Big trends of generating electricity with alternative and renewable resources has promoted the formation of distribution networks subsystems or micro grids, capable of supplying their own electric demand and to export energy to the interconnected system, if necessary. However, the effects of these generation units into the network and into the microgrid as well are many, as harmonic distortion, voltage flickers and especially in electrical protections.This paper provides an overview about implementation of renewable energy and distributed generation worldwide, as well as an introduction to microgrids concept and its main impacts and challenges into the electric systems. Finally, the main impacts of microgrid on protection equipments are presented at a distribution level, being adaptive protections one of the solutions to the dynamic changes of the electric system.
This work presents the development of 3D computational models that represent two studies about in-vitro cellular experimentation of cell stimulated by magnetic and electric field. The development considered the construction of the stimulation devices, the cell seeding, and the creation of the 3D computational models representing the arrangements. The models and their electromagnetic analysis were done in the ANSYS program. The volumes considered were: source of stimulation, Falcon cell culture plate, cell content, and space for zero potential. The electric field stimulation model considered an applied electric field between 250 V/m and 1 kV/m. While the magnetic field stimulation model considered an applied magnetic field between 0.5 mT and 2.0 mT. For both models, the frequency range was between 5 Hz and 105 Hz. As a result, the error between the stimulation devices and the created models was lower than 5%. The homogeneous area of the magnetic and electric field was established and the behavior of field strength produced by the stimulation devices was the expected one. In both models, the induced current density was the variable evaluated in the cellular material. The current density induced by the applied magnetic field was greater than by the applied electric field.
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