Reliability evaluation of power network: A case study of Fiji Islands

The reliability of electrical power network is the driving force for the development of a country Nowadays most electrical power industries and companies are working for the better satisfaction of the customers while considering the associate cost. Utility companies must have precise information concerning system performance to achieve these goals, consequently guarantee the assets maintenance. The reliability standard of electric power delivered to the customer in Fiji is still in developing stage. Hence it is obvious to have a thorough understanding on the present situation of Fiji islands. In this paper, the performance of electricity delivered being evaluated using commonly used reliability indexes. So that modification and improvement can be done to enhance reliability of Fiji Islands' power network

Vehicle to grid system to design a centre node virtual unified power flow controller

Centre node unified power flow controller can fulfil various power flow control objectives, such as the needs of reactive shunt and series compensation, phase shifting and ensure higher degree of control freedom. However, as they are expensive, they are not widely used. The potential of a low-cost solution that utilises the capabilities of plug in electric vehicle (PEV) in vehicle-to-grid mode of operation for the design of a centre node virtual unified power flow controller (CVUPFC) using PEV charging stations is explained. Simulations are performed to establish that the proposed CVUPFC improves the power quality utilising PEV charging stations as DC bus for the converters with higher degree of freedom to control

A medium frequency transformer with multiple secondary windings for medium voltage converter based wind turbine power generating systems

Recent advances in magnetic materials have led to the development of compact and light weight, medium and high frequency transformers, which would be a possible solution to reducing the size and weight of wind turbine power generating systems. This paper presents the overall design and analysis of a Metglas amorphous alloy 2605SA1 based medium frequency transformer to generate the isolated balanced multiple DC supplies for medium voltage converter systems. A comprehensive electromagnetic analysis is conducted on the proposed design based on experimental results. The test stand, data analysis, and test results are discussed. © 2013 American Institute of Physics

A review of human error in marine engine maintenance

Maritime safety involves minimizing error in all aspects of the marine system. Human error hasreceived much importance, being responsible for about 80% of the maritime accident worldwide. Currently,more attention has been focused to reduce human error in marine engine maintenance. On-board marineengine maintenance activities are often complex, where seafarers conduct maintenance activities in variousmarine environmental (i.e. extreme weather, ship motions, noise, and vibration) and operational (i.e. workoverload and stress) conditions. These environmental and operational conditions, in combination with generichuman error tendencies, results in innumerable forms of error. There are numerous accidents that happeneddue to the human error during the maintenance activities of a marine engine. The most severe human errorresults in accidents due to is a loss of life. Moreover, there are other consequences too such as delaying theproductivity of marine operations which results in the financial loss. This study reviews methods that arecurrently available for identifying, reporting and managing human error in marine engine maintenance. As abasis for this discussion, authors provide an overview of approaches for investigating human error, and adescription of marine engine maintenance activities and environmental and operational characteristics

Design of LMS algorithm for noise canceller based on FPGA

This paper presents the design of an adapting filtering method to remove the noise in the biomedical signal records. The major concern about analyze the presence of various artifacts in ECG records and modular artifacts in EEG records caused due to various noise factors. Here, we have proposed a design based on LMS (Least Mean Square) algorithm to remove the artifacts from biomedical signal using Verilog HDL based on been mapped on  commercially available FPGAs (Field Programmable Gate Arrays). In this design the LMS algorithm used as a noise canceller and the reference signal was adaptively filtered and subtracted from primary signal to obtain the estimated biomedical signal. The original biomedical signal can be reconstructed by passing the digital bit stream through a low pass filter. This design is suitable for its low power biomedical instrument design and it reduces the whole system cost. Keywords: LMS algorithm, noise canceller, Verilog HDL, artifacts, biomedical signal, Low power application

Aromatic network for power distribution system

Electricity is an essential part of our existence in present days but inconsistent supply of electricity during tropical cyclones and natural disasters or fault in grid can create a dilemma over our life style, especially for remote area or island and even for the entire nation. These problems can be addressed at the distribution level by using smart, self-controlled and resilient micro electric grid that can operate on its own as microgrid or with grid connected mode as distribution network and energized by Renewable Energy Sources (RES). Three different designs of distribution network are commonly used and modified as microgrid structure which are: radial network, ring/loop network and mesh network architecture. Each of them has serious drawbacks to work during the disaster situations especially during the tropical cyclone or even snowstorm. To overcome these situation; a novel distribution network with better control and management techniques is designed here which is intrinsically potential for the future power systems to achieve reliability, efficiency and quality power supply even during the disaster. This design is essentially inspired by natural structure of an aromatic molecule which could be applied in the grid structure that would be strong enough to withstand any unexpected situations or faults. The novel network structure is represented as an aromatic molecule, like dichlorodiphenyltrichloroethane (DDT) where hexagonal benzene is the basic element for the network. This aromatic structure and the properties of the compound are used as the concept of the proposed design for the distribution network to ensure better stability and resiliency. Moreover, self-healing mechanism is embedded in the distribution system to minimize system interruptions during common faults. Finally, to maximize energy efficiency and reduce human effort, smart wireless communication system, effective control technology and switching of distributed generations (DG’s) with respect to demand and consumption have been included in this network design

An amorphous alloy core medium frequency magnetic-link for medium voltage photovoltaic inverters

The advanced magnetic materials with high saturation flux density and low specific core loss have led to the development of an efficient, compact, and lightweight multiple-input multiple-output medium frequency magnetic-link. It offers a new route to eliminate some critical limitations of recently proposed medium voltage photovoltaic inverters. In this paper, a medium frequency magnetic-link is developed with Metglas amorphous alloy 2605S3A. The common magnetic-link generates isolated and balanced multiple DC supplies for all of the H-bridge inverter cells of the medium voltage inverter. The design and implementation of the prototype, test platform, and the experimental test results are analyzed and discussed. The medium frequency non-sinusoidal excitation electromagnetic characteristics of alloy 2605S3A are also compared with that of alloy 2605SA1. It is expected that the proposed new technology will have great potential for future renewable power generation systems and smart grid applications. © 2014 AIP Publishing LLC

Impact of Stray Voltage on Renewable Energy-based Farm in Pacific Island Country

Recent advancements in solar technology offer an enormous opportunity for the people of Pacific Islands to use electricity from the off-grid solar system for both their energy needs and farming activities. However, a farm’s productivity and animal health might be seriously threatened if it experiences stray voltages caused by the improper grounding of its installed electrical systems. As a shift in the neutral point of an electrical system creates a current flow to the ground through conducting elements, the impacts of stray voltages need to be addressed from both technical and economic viewpoints. In this research, the effects of stray voltages passing through animals are explored using circuit designs for solar sources considering variable grounding resistances due to the different body resistances of various types of animals, and environmental and grounding design issues. A comparison of the stray voltages of two different sources (off-grid solar and traditional grid) with various configurations are conducted to determine their effects on a farm. Finally, their economic impacts together with possible techniques for mitigating them are explained

Synthesis of some bis-triazole derivatives as probes for cytotoxicity study

A series of bis[4-N-amino-5-mercapto-1,2,4-triazol-3-yl] alkanes (1a-e) and their Schiff bases with 2-adamanta-none (2a-d) and bis [1, 2, 4-triazolo [3, 4-b] - 1, 3, 4-thiadiazol-4-yl] alkanes (3a-e) have been synthesized with high yields. The cytotoxicity study of these newly synthesized compounds against brine shrimp lethality test as well as Structure-Activity-Relationship (SAR) has been discussed

Synthesis of hydantoin and thiohydantoin related compounds from benzil and study of their cytotoxicity

Condensation of benzil (1) with urea, monophenyl urea and diphenyl urea in the presence of absolute ethanol using 30% aqueous NaOH gave the products 1a, 1b and 1c respectively and also with thiourea, monomethyl thiourea, dimethyl thiourea and diethyl thiourea the products 2a, 2b, 2c and 2d were obtained. Methylation of the product, 2a in the presence of dimethyl formamide (DMF) using K2CO3 formed 2. The compounds 1b, 1c, 2b, 2c and 2 showed highly cytotoxic activity and the compounds 1a, 2a, 2d showed relatively low cytotoxic activity against brine shrimp lethality bioassay