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The paper deals with the modeling and analysis of low voltage (LV) power distribution networks feeding residential, commercial and small industrial consumers including distributed generation units and storage systems. It focuses on an optimization model for the energy management system of the experimental microgrid built at the University of Applied Sciences and Arts of Western Switzerland, HES-SO...
The paper deals with the performance of overhead distribution lines against indirect lightning. The lightning performance, i.e. the annual occurrence of lightning events potentially able to cause insulation flashovers, can be assessed by means of statistical procedures capable to account for the probabilistic distribution of the most influent parameters, among which those that describe the waveform...
This paper presents an analysis of the reduction effect on the amplitude of lightning-induced overvoltages in an overhead line due to nearby buildings. Such an affect can be appraised by means of a finite element method (FEM) model. A method already proposed by the authors, based on the use of weighting functions applied to the static, induction and radiation terms of the expressions of the lightning...
In urban areas the presence of buildings is expected to reduce the amplitude of lightning induced voltages on overhead lines with respect to the case of open terrain. This paper presents a method for estimating such a reduction effect. For this purpose weighting functions are applied to the electrostatic, induction and radiation terms of the expressions adopted for the lightning electromagnetic field...
The impact of the increasing connection of distributed generation to medium voltage (MV) distribution feeders, with particular reference to photovoltaic (PV) units, justifies the application of an adaptive control of voltages and reactive power flows. This paper describes the analysis of a voltage/var control (VVC) structure that includes the cooperative control of the reactive power regulators of...
When assessing the lightning performance of distribution lines, major attention is in general devoted to the induced voltages from nearby strikes rather than to direct events hitting the line, as the latter are always expected to cause a fault in the line. This paper proposes a Monte Carlo procedure capable to make it possible the evaluation of the overvoltage probability due to both indirect and...
The paper describes the co-simulation platform that integrates a mobility simulator adapted to represent e-mobility with a dynamic simulator of the power distribution network and with an UMTS communication network simulator. The platform appears useful in order to assess the effects of the transients caused by the concurrent charging of a large number of electric vehicles to the operating conditions...
CIGRE TB 549 (2013) is an update on previous CIGRE documents on the subject, published in Electra more than three decades ago. Lightning parameters needed in different engineering applications are reviewed. New experimental data, as well as the old data, are evaluated. Additional lightning parameters, previously not considered by CIGRE, are included. Possible geographical and seasonal variations in...
One of the challenging tasks related to the realtime control of Active Distribution Networks (ADNs) is represented by the development of fast (i.e. sub-second) state estimation (SE) processes. As known, the problem of SE of power networks links the measurements performed in the network with a set of non-linear equations representing the links between the network node voltage phasors (i.e. the system...
Two approaches for the numerical solution of the full-wave Maxwell's equations, based upon the finite element method and the method of moments, are here used for the computation of lightning induced voltages on overhead distribution power lines. The methods are well suited to consider both induced and conductive coupling mechanisms between the lightning return stroke channel, the overhead line conductors...
A joint research project between AES Sul, the Federal University of Itajubá and the University of Bologna aims at defining the required protections against lightning-originated overvoltages in a resonant grounded distribution system in order to achieve the adequate lightning performance level with minimum cost. The paper aims at illustrating the effectiveness of the presence of a surge arrester or...
Unplanned power system islanding is usually seen as a major risky operating condition and specific countermeasures are applied in order to avoid it. However the capability of voluntary disconnection from the external grid and autonomous operation is often a requirement for some industrial power systems and power plants. The panel session at the 2012 IEEE Innovative Smart Grid Technologies Conference...
The aim of the paper is to analyze overvoltages in overhead distribution lines induced by nearby lightning return stroke currents taking into account also the conductive coupling between the lightning current injected into the soil and the line's grounding system. Experimental results obtained in 2003 at the International Center for Lightning Research and Testing (ICLRT) in Florida have shown that...
The paper presents a microcontroller-based automatic system that applies the continuous wavelet analysis to the measured fault-originated electromagnetic transients in order to locate phase-to-ground faults in power distribution networks composed by coaxial cables. The paper describes the numerical procedure conceived to: (i) detect the presence of fault-originated transients superimposed to steady-state...
As known the lightning incidence of a vertical structure is related to the physical processes involved in the final stage of the progression of the downward lightning leader to the structure and upward streamers, in case downward flashes are taken into account. Within this context, the paper presents and discusses a numerical implementation based on the Finite Element Method (FEM) of the Leader Progression...
A two-year experimental campaign on lightning-originated disturbances carried out in an Italian rural region characterized by a high ground flash density (4 flashes/km2/yr) has provided a set of voltage transient measurements in a medium voltage (MV) feeder that are clearly correlated with both specific events detected by the Italian lightning location system (LLS) CESI-SIRF and sequences of relay...
The paper aims at illustrating a procedure for the lightning risk assessment of industrial oil process plants. The procedure is based on the use of the Monte Carlo method and applies to each event both a lightning attachment criterion and a damage calculation model. In particular, for the case of oil tanks, the model calculates the expected annual number of damages associated to the metal melting...
The paper describes a phasor measurement unit (PMU) prototype based on a synchrophasor estimation technique specifically conceived for active distribution networks and the experimental results obtained by its application during intentional islanding and reconnection tests of a set of urban feeders. As proved by the laboratory experimental characterization of the developed PMUs, very low values of...
The latest distribution management systems tend to incorporate optimization functions for the short-term scheduling of the various energy and control resources available in the network (e.g., embedded generators, reactive power compensators and transformers equipped with on-load tap changers). The short-term scheduling procedure adopted in the paper is composed by two stages: a day-ahead scheduler...
The paper presents a microcontroller-based automatic scheduling system for the operation and control of the distributed energy resources connected to residential electric power installations, taking into account both the following operating conditions: 1) the grid connected operating mode, in which the household electric circuits are connected to the distribution network; and 2) the islanded operating...
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