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Recent works have highlighted the growth of battery energy storage system (BESS) in the electrical system. In the scenario of high penetration level of renewable energy in the distributed generation, BESS plays a key role in the effort to combine a sustainable power supply with a reliable dispatched load. Several power converter topologies can be employed to connect BESS to the grid. There is no defined...
The paper presents an experimental investigation on the efficiency of different underground transmission/distribution line magnetic shielding techniques. Measurement results of magnetic field and temperature rise around the cable conductors are shown. An analysis of the thermal effects of each shielding technique on the line power capacity is presented. The experiments were performed on a test site...
The problem of computing the harmonic currents produced by nonlinear loads has been constantly raised in the field of power quality. Such a problem becomes even more difficult when the voltage supply has already been polluted with harmonics. This context is further investigated in this work by presenting measurement results showing how the harmonic currents generated by a nonlinear load can depend...
This paper analyzed the effect of the multi-grounded neutral on the peak values and waveforms of the lightning induced voltages (LIVs) in an overhead power distribution line. The results show that the LIV waveforms observed close to a neutral grounding point are smooth, while those observed around the mid-point between two consecutive grounding points are oscillatory. The waveform oscillations are...
This paper aims at contributing to the study of grounding systems behavior due to direct lightning currents striking rural distribution lines located in high flash density areas. The high current density, from direct flashes, causes soil ionization phenomenon in grounding systems. In order to investigate the ionization phenomenon under various grounding conditions, impulse tests were performed on...
The replacement of wooden crossarm as insulation and structural part in rural distribution networks structures has been tackled by several power utilities around the world. UFMG has conducted a research work, supported by CEMIG-D (a major power utility in Brazil), on this issue evaluating alternatives to the present standard which is based on wooden crossarms. Several alternatives were considered...
This paper presents the front time and time-to-half values of lightning induced voltages obtained from deterministic and probabilistic simulations. The lightning induced-voltages are calculated at the center of an overhead line above lossy ground, considering typical parameters for first negative strokes. The waveshape parameters are influenced by the distance from the stroke striking point to the...
The lightning induced voltages on aerial and underground lines depend on the value of soil resistivity. Most calculating methodologies were developed considering the soil as a homogeneous and isotropic medium. However, actual soil is better represented if stratified into horizontal layers of different resistivity values. This paper presents a simplified expression for the calculation of the resistivity...
This work describes a system for the measurement of the transient impedance of ground electrodes using a portable impulse generator and a new measuring arrangement. The innovation is the use of a very short current reaction lead, which is possible due to the use of transmission line with very low propagation velocity (3% of the velocity of light). The methodology for obtaining the transient impedance...
The reduced model is a method to study lightning by means of analog simulation. This method reproduces in laboratory or in appropriate conditions the real phenomenon, in scale. The most papers using the reduced model use a lossless channel to model the discharge channel. This paper proposes to evaluate an alternative model to the discharge channel: the lossy channel. The benefits of using such a model...
This paper presents a time-domain method for the calculation of the electric field at the surface of earth due to lightning, when the earth structure is made of two parallel horizontal layers of finitely conducting earth. The method is based on the assessment of the electric field at the surface considering the earth as homogeneous and with the electrical parameters of the first layer. The contribution...
This paper presents the calculation results of lightning induced voltages on overhead lines using two different formulations for the horizontal electric field at the earth surface. The first one is a time-domain equation equivalent to the surface impedance contained in the Cooray-Rubinstein formula, while the second one is an improved equation that provides more accurate results in the vicinity of...
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