Influence of Resolution of the Input Data on Distributed Generation Integration Studies

One of the main issues concerning large penetration of the renewable energy based generators on the distribution network is related to the voltage variations due to intermittent character of the solar irradiance and wind. The actual power quality standards provide only general information regarding the evaluation procedure of the voltage fluctuations and no directions regarding the sampling frequency of the data used. As a consequence, most of the studies neglect effect of the solar irradiance and wind speed in fast changing conditions on the utility grid. This work proposes a methodology to evaluate the voltage fluctuations into the low voltage distribution network caused by variable generation and reveals the influence of data resolution on the final results. A short review regarding the assessment of the voltage variations is presented in advance and an appropriate model of the power system is build, including the generating units that are capable to operate with high resolution input data. Real parameters for the components of the simulated system are used in order to obtain realistic results.</p

Improved protection system for phase faults on marine vessels based on ratio between negative-sequence and positive-sequence of the fault current

This paper presents a new method to protect the radial feeders on marine vessels. The proposed protection method is effective against Phase-Phase (PP) faults and is based on evaluation of the ratio between the negative-sequence and positive-sequence of the fault currents. It is shown that the magnitude of the introduced ratio increases significantly during the PP fault, hence indicating the fault presence in an electric network. In this paper, the theoretical background of the new method of protection is firstly discussed, based on which the new protection algorithm is described afterwards. The proposed algorithm is implemented in a programmable digital relay embedded in a Hardware-in-the-Loop (HIL) test setup that emulates a typical maritime feeder using a Real Time Digital Simulator (RTDS). The HIL setup allows testing of the new protection method under a wide range of faults and network conditions and the experimental results demonstrate its effectiveness in all scenarios conducted. The proposed protection method offers a solution to the protection challenges associated with variability of the short-circuit currents in radial feeders, advancing in this way the traditional mean of protection in maritime feeders, represented by OverCurrent (OC) relays

FT-IR Studies of Cerium Oxide Nanoparticles and Natural Zeolite Materials

An emerging topic of our days is nanoscience and nanotechnology successfully applied in the food industry. Characteristics such as size, surface area and morphology can modify the basic properties and the chemical reactivity of the nanomaterials. The breakthrough of innovative materials, processes, and phenomena at the nanoscale, as well as the progress of new experimental and theoretical techniques for research, supply novel opportunities for the expansion of original nanosystems and nanostructured materials. These study examine two types of nanoparticles, namely cerium oxide nanoparticles (CeO2 NP) and natural zeolites. In view of the importance of CeO2 NP in various biological applications, the primary objective of this study is to characterise four samples of CeO2 NP in order to understand the role of the synthesis process in the final product. Nanocrystalline natural zeolites are materials with interesting properties which allows them to be used as adjuvant in many therapies. The characterisation of CeO2 NP and two types of natural zeolites using Fourier Transform Infrared (FT-IR) spectroscopy is described. Therefore, this study examined two types of nanomaterials, namely cerium oxide nanoparticles and zeolites, for further applications on microorganisms and living cells