Engineered carbon-based scaffolds for hard and soft tissue repair, reconstruction or regeneration
Microgrids (MGs) are important because of their ability to provide a greener" solution to obtain reliable, secure and sustainable electricity from renewable sources of energy. As a MG can be islanded (i.e. disconnected from the main grid), the power quality issues observed are very different when compared to the traditional centralized grid. These issues are of significant importance because the reliability of the grid is impacted by the MG operation. Currently, the typical power quality issues such as total harmonic content and transient stability have been studied only for an ideal voltage source of constant magnitude - assumed to be the distributed generator (DG) connected to a grid. However, under practical conditions, a MG might have more than one DG (Example: solar, wind, diesel generators, and CHP, among others) connected to it and some of these DGs would be subject to varying output throughout the day based on changes in intensity of solar radiation, wind speed, and other environmental factors. The current research takes this into account and examines the efficacy of an existing power quality control strategy for a MG consisting of a stochastically modeled renewable energy source i.e. a solar PV array. A Robust Servomechanism Controller in conjunction with a Discrete Sliding Mode Controller is employed to achieve voltage and current regulation in the MG. Stochastic model of a solar PV array along with a supplemental DC voltage source model have been presented in this research. The solar PV array utilizes actual TMY3 irradiance data for Dayton, Ohio. The supplemental DC voltage source is connected in series with the solar PV output and helps to compensate for the intermittent nature of energy produced by the solar PV array. A cost-based approach to connecting and disconnecting the MG from the utility supply whilst ensuring the maximum use of incident solar energy is also presented in this research. The MG model developed in Matlab Simulink® follows the Consortium for Electric Reliability Technology Solutions (CERTS) architecture for modeling MGs. The examination of the efficacy of an existing control strategy in a MG topology capable of making real-time cost-based decisions is expected to help the practical implementation of MGs."