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Fault Management System (FMS) is one of the main functions in Distribution Automation System (DAS); however, the conventional FMS cannot be used in distribution systems with Distributed Generators (DGs) due to the lack of directional function. The directional fault detection device is expensive due to the expensive directional module used. In a wide-ranging distribution system, the investment cost will be very high if the fault detecting devices are expensive. Therefore, the design and implementation of a cost-effective FMS for distribution system with DGs is necessary. A Multi-Level Fault-Current Indicator (MLFCI) having a plurality of reed switches used to detect different current levels is proposed in this paper. The hardware prototype is designed and implemented. An algorithm used to locate fault based on the different fault current levels is derived. A MLFCI-based FMS for distribution systems with DGs is then realized. Experimental results demonstrate the feasibility of the proposed MLFCI. Simulation results are then used to demonstrate the validity of the proposed MLFCI-based FMS for distribution systems with DGs. [ABSTRACT FROM AUTHOR]

Abstract: This paper tries to use USB and personal digital assistant to develop a novel power quality (PQ) monitoring platform and then integrates GPRS technique into the proposed PQ platform to realize a wide-area PQ monitoring and report-back system. The works of this paper can be divided into three parts. First, a small-scale PQ monitoring platform with appropriately designed I/O interfaces and peripherals is designed and implemented. Next, a GPRS module which can be integrated into the designed PQ monitoring platform is developed. Finally, a web server with well-designed database and web human–machine interfaces used to record abnormal PQ data and display PQ data are designed. The proposed GPRS-based wide-area PQ monitoring and report-back system can be used for PQ monitoring with minimum cost and maximum efficiency. All the functions implemented in this paper can realize the novel, real-time and wide-area PQ monitoring. Experimental results demonstrate the validity of the proposed system. [Copyright &y& Elsevier]

Abstract: Distributed generator (DG) resources are small, self-contained electric generating plants that can provide power to homes, businesses or industrial facilities in distribution feeders. They can be used to reduce power loss and improve service reliability. However, the values of DGs are largely dependent on their types, sizes and locations as they were installed in distribution feeders. A value-based method is proposed in this paper to enhance the reliability and obtain the benefits for DG placement. The benefits of DG placement described in this paper include power cost saving, power loss reduction, and reliability enhancement. The costs of DG placement include the investment, maintenance and operating costs. The proposed value-based method tries to find the best tradeoff between the costs and benefits of DG placement and then find the optimal types of DG and their corresponding locations and sizes in distribution feeders. The derived formulations are solved by a genetic algorithm based method. Test results show that with proper types, sizes and installation site selection, DG placement can be used to improve system reliability, reduce customer interruption costs and save power cost; as well as enabling electric utilities to obtain the maximal economical benefits. [Copyright &y& Elsevier]

Abstract: In a competitive electric energy market, service quality and reliability are two of the essential issues of the business. Distribution automation has been chosen by many utilities around the world as one of the most reliable measures for reducing outage time in their distribution networks. Considering network reliability data and the customer interruption costs, a value-based planning method is proposed in this paper to find the optimal numbers and locations of switches in feeder automation systems. The proposed method takes reliability costs, maintenance and investment costs into account to obtain a feeder automation plan that has a maximum benefit and a proper system reliability requirement. Three stages are involved in the search for optimal solution. Using minimum feeder data and assume equally distributed feeder loads, stage 1 gives initial estimates of reliability indices and costs, and benefit/cost ratios of different feeder automation options. To gain the maximum benefits from feeder automation with reasonable costs, results of stage 1 are used to select feeders with highest priorities for automations. Stage 2 determines the optimum locations of switches that minimize feeder outage costs, and in stage 3, the best locations for tie switches in the automated network are determined. Numerical processing procedure is described and the solution efficiency and results are compared with those obtained from a genetic algorithm. [Copyright &y& Elsevier]

Abstract: This paper proposes a systematic method to allocate the power flow and loss for deregulated transmission systems. The proposed method is developed based on the basic circuit theories, equivalent current injection and equivalent impedance. Four steps are used to trace the voltages, currents, power flows, and losses contributed by each generator sequentially. Using this method, the real and reactive power on each transmission lines and their sources and destinations can be calculated. The loss allocation of each line, which is produced by each generator, can also be obtained. Test results show that the proposed method can satisfy the power flow equation, the power balance equation and the basic circuit theories. Comparisons with previous methods are also provided to demonstrate the contributions of the proposed method. [Copyright &y& Elsevier]