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This paper addresses a new approach for real-time short circuit analysis of radial and weakly meshed distribution networks. The approach works based on a well documented radial power flow study method, and uses a hybrid compensation method to account for loops, PV nodes, and fault currents simultaneously. The three-phase short circuit analysis, in its actual a-b-c phase representation, can be applied to balanced or unbalanced distribution systems. A distribution short circuit program which is developed based on this approach, is integrated with a three-phase power flow program to solve various types of single or simultaneous faults, including single-line to ground, three-line to ground, double-line to ground, line-to-line, and double three-line to ground faults. Results of the application of this approach to large-scale distribution networks are also reported in this paper. Keywords: distribution short circuit analysis, real-time distribution system protection, compensation method.

The special publication was prepared by the Power System Relaying Committee of the IEEE to assist people involved in the installation, application, and operation of utility-interconnected dispersed storage and generation (DSG) systems of 500 kW or less. The energy sources considered are * Batteries * Fuel Cells * Windmills * Photovoltaic Arrays In most cases, the electrical energy produced is direct current, dc, which must be converted to alternating current, ac, for connection to the electric utility network. The interface between the dc source and the utility ac is often a static power converter (SPC). The purpose of the publication is to illustrate those SPC characteristics that can obviate the need for the interface relay protection package normally required by a utility. A qualifying SPC can detect utility system disturbances or other conditions that would require generator separation in addition to its normal function of protection and control of the DSG.

Working Group D10 Applications of Expert Systems to Power System Protection of the Line Protection Subcommittee, Power System Relaying Committee, was organized in 1989 with the following assignment as finally adopted: Survey expert system technology to identify suitable and significant applications to power system protection. Write a technical paper that introduces protection engineers to expert systems and describes several potential applications. This paper represents the work performed by the Working Group in fulfilling its assignment. The paper is divided into sections that describe a number of potential applications thought to be significant by the members of the Working Group.

The number, type and location of the protective devices on a distribution feeder have a direct effect on the system reliability. In earlier work, a technique was developed to design a protective system in order to minimize the SAIFI index. This paper extends earlier results by using a goal programming approach to achieve compromises among various engineering objectives. The design goals are: a) to minimize the SAIFI and ASIFI indices by identifying types and locations of protective devices and b) to achieve a reasonable trade-off between a decrease in the SAIFI index and an increase in MAIFI index by identifying where a fuse saving scheme should be applied. Numerical examples highlight the approach. Index Terms--Distribution reliability, distribution systems, fuzzy optimization, goal programming, integer programming, linear programming, protection design.