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This paper presents a time-domain model of a MV/LV bidirectional solid state transformer (SST). A multilevel converter configuration of the SST MV side is obtained by cascading a single-phase cell made of the series connection of an H bridge and a dual active bridge (dc-dc converter); the aim is to configure a realistic SST design suitable for MV levels. A three-phase four-wire converter has been used for the LV side, allowing the connection of both load/generation. The SST model, including the corresponding controllers, has been built and encapsulated as a custom-made model in the ATP version of the EMTP for application in distribution system studies. Several case studies have been carried out in order to evaluate the behavior of the proposed SST design under different operating conditions and check its impact on power quality. [ABSTRACT FROM AUTHOR]

This paper presents a Monte Carlo approach for reliability assessment of distribution systems with distributed generation using parallel computing. The calculations are carried out with a royalty-free power flow simulator, OpenDSS (Open Distribution System Simulator). The procedure has been implemented in an environment in which OpenDSS is driven from MATLAB. The test system is an overhead distribution system represented by means of a three-phase model that includes protective devices. The paper details the implemented procedure, which can be applied to systems with or without distributed generation, includes an illustrative case study and summarizes the results derived from the analysis of the test system during one year. The goal is to evaluate the test system performance considering different scenarios with different level of system automation and reconfiguration, and assess the impact that distributed photovoltaic generation can have on that performance. Several reliability indices, including those related to the impact of distributed generation, are obtained for every scenario. [ABSTRACT FROM AUTHOR]

This paper is aimed at assessing the impact of unintentional islanding operations (IOs) in the presence of large induction motors (IMs) within distribution networks (DNs). When a fault occurs, following the circuit breaker (CB) fault clearing, the IMs act transiently as generators, due to its inertia, until the CB reclosing takes place. The present work is the outcome of a project carried out in a small DN, where field measurements were recorded over two years. This paper provides a detailed description of the test system, a selected list of field measurements, and a discussion on modeling guidelines used to create the model of the actual power system. The main goal is to validate the system model by comparing field measurements with simulation results. The comparison of simulations and field measurements prove the appropriateness of the modeling guidelines used in this work and highlight the high accuracy achieved in the implemented three-phase Matlab/Simulink model. [ABSTRACT FROM AUTHOR]