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This paper introduces a fault location algorithm, which is appropriate for unbalanced power distribution systems with distributed generation of any type (i.e., synchronous machines and inverter-based units). The proposed algorithm is based on three-phase circuit analysis and utilizes unsynchronized voltage and current measurements taken from the connection points of the sources. The source impedances are not required to be included in the bus impedance matrix formulation. The algorithm accurately estimates the fault position, the fault resistance and the synchronization angles. Moreover, the algorithm can successfully identify the most possible fault location candidate among multiple choices. Extensive simulation studies demonstrate a very good performance of the proposed fault location algorithm for any fault type under various parameters that may influence its accuracy. [ABSTRACT FROM AUTHOR]

This paper presents the detailed engineering study conducted to design a high-impedance restricted earth fault (REF) scheme for four 11/0.415-kV, Dyn11, and 2500-kVA power transformers in an industrial power system. Analytical calculations carried out to specify the components constituting the REF scheme and to determine the appropriate relay settings are provided. The proposed REF scheme is evaluated using reliable Alternative Transients Program–Electromagnetic Transients Program simulations. The obtained results validate the adequacy of the design and highlight the advantages of using such a protection, such as fast and reliable operation even under severe current transformer saturation conditions. [ABSTRACT FROM PUBLISHER]

This paper puts forward a novel algorithm for locating faults on double-circuit transmission lines using two-end unsynchronized current measurements. The algorithm does not require line parameters, which is a radical step forward compared to existing approaches, which require this information, so it can be considered as a settings-free algorithm. Only the positive-sequence current phasors during the fault are processed for determining the sought distance to fault and the synchronization angle, limiting thus the amount of data needed to be transferred from each line terminal. The proposed algorithm is derived by applying the Kirchhoff's voltage law around the parallel circuits loops during the fault. The algorithm is applicable for both transposed and untransposed double-circuit lines and is independent of the fault type. Evaluation studies using reliable Alternative Transients Program-Electromagnetic Transients Program simulation data verify that the accuracy of the proposed algorithm is very high under various fault resistances, fault locations, and source impedances. [ABSTRACT FROM AUTHOR]

This paper puts forward a novel algorithm for locating faults on power transmission lines without requiring line parameters. The algorithm utilizes unsynchronized measurements of voltages and currents from both ends of a transmission line and is formulated in terms of the fundamental frequency phasors of the measured signals. Both prefault and postfault phasors are processed for determining the sought distance to fault and the synchronization angle. The calculations are performed initially for a lumped parameter line model with neglecting shunt capacitance. Then, these results are used as starting values for an iterative process, where the impacts of the shunt capacitance of the line are considered. The proposed two-stage fault-location algorithm is applicable for transposed and untransposed transmission lines and is independent of the fault resistance and source impedances. Evaluation studies using reliable Alternate Transients Program–Electromagentic Transients Program simulation data verify that the proposed algorithm can yield quite accurate results. [ABSTRACT FROM PUBLISHER]

• A fault location algorithm based on standard bus-impedance matrix and fault theory is proposed for application in active distribution systems. • Synchronized voltage measurements from only two measurement points inside the distribution system are required. • The proposed fault location algorithm is adequate for all types of common faults and all types of DG units (i.e. synchronous-machines-based and inverter-interfaced units). • Simulation results show a good performance of the fault location algorithm under various pre-fault operation conditions of a test distribution system. This paper addresses a fault location algorithm appropriate for unbalanced medium voltage overhead distribution systems with or without distributed generation. The proposed algorithm utilizes only synchronized voltage measurements from two measurement points inside the distribution system. The algorithm accurately estimates the fault position for any type of short-circuit faults by applying fundamental bus-impedance-matrix-based fault analysis. Fault resistance is considered in the algorithm but not explicitly included in the bus impedance matrix. Simulation results show a good performance of the fault location algorithm under various pre-fault operation conditions of a test distribution system. [ABSTRACT FROM AUTHOR]

Abstract: During the last 15 years, a series of food scares and crises (BSE, dioxin, foot and mouth disease) have seriously undermined public confidence in food producers and operators and their capacity to produce safe food. As a result, food safety has become a top priority of the European legislative authorities and systems of national food control have been tightened up and have included the establishment of the European Food Safety Authority. In Greece a law creating the Hellenic Food Safety Authority has been approved. The main objectives of this Authority are to promote the food security to consumers and inform them of any changes or any development in the food and health sector. The paper reviews the general structure of the current food control system in Greece. It describes the structure and the mission of the Hellenic Food Safety Authority and explains the strategy to carry out inspections and the analysis of the preliminary results of such inspections. Details are also given of the personnel training and certification and accreditation standards to be met by the Authority by the end of 2004. [Copyright &y& Elsevier]