A Mixed Integer Linear Programming Approach to the Optimal Reconfiguration of Electrical Distribution Networks with Embedded Generators

The paper focuses on the solution of the minimum loss reconfiguration problem of distribution networks, including embedded generation, by means of a mixed integer linear programming (MILP) model. The proposed model takes into account typical operating constraints of distribution networks (radial configuration, branch ampacity limits and bus voltage requirements). The accuracy of the results and the computational performances of the proposed MILP model are evaluated by making reference to test networks already adopted in the literature for the problem of interest

A Synchrophasor Estimation Algorithm for the Monitoring of Active Distribution Networks in Steady State and Transient Conditions

The paper presents a PMU prototype specifically developed for active distribution network applications. The paper describes the method developed to accurately measure the synchrophasors, its implementation into a real-time microcontroller and the relevant characterization in both steady state and transient conditions. Concerning these last points, the paper presents a test procedure suitably conceived to characterize the PMU with both steady state – single tone and distorted – and frequency-varying signals simulating power systems electromechanical transients. The results show that the developed PMU exhibits high accuracy levels that are not modified by the harmonic distortion of the reference signal and by its frequency-varying transient behavior and compatible with their use into power distribution networks

Chapter 14 - Restoration Processes after Blackouts

This chapter aims at illustrating the power system dynamic behavior during restoration scenarios in transmission networks, with particular reference to the analysis of thermal power plant black-start capabilities. This chapter is structured into three parts. Section 14.2 briefly reviews the requirements and the structure of power system restoration processes. The unbundling and liberalization of electrical power systems justifies the reassessment of power system restoration strategies, also by increasing the number of black-start resources, traditionally only represented by hydro stations and gas turbines (GTs). Hence, Section 14.3 deals with the analysis of the black-start capabilities of thermal stations equipped with both steam turbines (STs) and GTs. Moreover, accurate modeling of the dynamic interaction between the power plant and the restoring electrical power system, throughout the use of modern computer simulation tools, appears to be of considerable help to study the early stage of the restoration plans and to design specific control systems to support the feasibility and reliability of black-start maneuvers. Therefore, Section 14.3 also includes the analysis of the typical transients occurring during load restoration maneuvers and islanding formation for two representative types of power plants, namely a once-through boiler steam group repowered by a gas turbine and a combined combined-cycle unit. The models of the two relevant simulators and their identification by means of experimental data are described in Section 14.4

Effects of nearby buildings on lightning induced voltages on overhead power distribution lines

For the case of urban overhead lines, the presence of nearby buildings is expected to affect the overvoltages induced by nearby cloud-to-ground lightning return strokes. So far, this effect has been seldom taken into account in the literature on the subject. The paper presents a 3D FEM model that calculates the lightning electromagnetic pulse (LEMP) taking into account the presence of a building placed in proximity of the LEMP-coupled overhead line. As a first approximation, all the metallic elements are assumed as perfect conductors, as well as the ground plane. The calculated fields are then introduced in the Agrawal et al. coupling model for the calculation of the induced voltages. The results of a sensitivity analysis carried by varying the model and dimensions of the building, its distance to the line and the position of the lightning stroke location are presented and discussed