Publications by Rafael Silva Alipio

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Grounding system design ensures safety compliance for transmission lines under lightning conditions. In this article, the transient response of short concrete encased grounding electrodes is investigated, that is, a 2.5 m vertical rod and a 10 m horizontal ...

This paper investigates the potential inaccuracies associated with using a modal-domain model featuring a real and frequency-independent transformation matrix in simulating electromagnetic transients on power overhead lines equipped with underbuilt wires. ...

This paper proposes closed-form expressions for the calculation of the ground-return impedance and admittance of underground cables. The proposed expressions are shown to reproduce the integral equations of Xue with great accuracy for a wide range of groun ...

This paper proposes a tower-foot grounding system model compatible with EMT programs which might be useful for the simulation of lightning transients in overhead lines. The proposed model is based on the solution of the telegrapher's equations and the appl ...

This paper proposes a novel integer-mixed probabilistic optimal power flow (IM-POPF) strategy for frequency regulation in islanded microgrids under uncertain operating conditions. Existing load-shedding approaches face critical limitations: continuous fram ...

This paper presents experimental results on the transient response of a buried insulated wire subjected to fast transient signals. It reports measurements of voltage and current at the sending end, as well as the voltage at the receiving end of the insulat ...

This study assesses the accuracy of the formulations of Carson and Sunde in modeling ground effects on overhead wires, particularly for high-frequency transients and high-resistivity soils. The results reveal that these traditional formulations tend to und ...

This paper proposes small-argument approximations for two closed-form equations that were recently derived for the calculation of the ground-return impedance and admittance of underground cables. The proposed expressions are shown to be accurate up to 1 MH ...

This paper presents a comprehensive assessment of the accuracy of high-frequency (HF) earth meters in measuring the tower-footing ground resistance of transmission line structures, combining simulation and experimental results. The findings demonstrate tha ...

In this paper, a rigorous and independent validation of two different approaches for calculating the ground-return impedance and admittance of multiconductor underground cable systems using the transmission line theory is carried out. Furthermore, analyses ...

Backflashover rate (BFR) is strongly dependent on the cumulative peak current distribution (CCD) adopted in the calculations. An original aspect of the present work is that such dependence is simultaneously assessed in estimating the probability of the cri ...

In this paper, a numerical formulation for solving the transmission line equations for a bare wire buried in a dispersive soil is derived. The formulation is developed using the finite-difference time-domain (FDTD) method, including the frequency-dependent nature of the soil electrical parameters. The soil electrical parameters are rigorously represented through the soil model proposed by Alipio and Visacro. It is shown that the results obtained with the proposed formulations are in good agreement with expe

The propagation characteristics along a single-conductor line above a lossy ground are assessed considering different formulations to compute the ground correction terms in the per-unit-length line parameters. It is shown that the often-used Sunde’s formul ...

This paper presents some results of simulation of the resulting ground potential rise (GPR) in wind turbine grounding systems in response to typical current pulses pertinent to upward negative lightning. The analyses consider two different current pulses, which are defined based on measured currents of upward flashes initiated from the instrumented Säntis Tower in Switzerland, namely: i) a fast pulse, similar to return strokes observed in downward negative lightning, and ii) a slow pulse associated with M-c

In recent years, the electromagnetic time reversal (EMTR) theory has been successfully applied for locating various sources of disturbances, such as short-circuit faults, in power systems. In this paper, a technique based on the EMTR is applied to locate defects in grounding electrodes. Analytical expressions are derived applying the transmission line equations in the frequency domain to the case of locating breakpoints on a simple horizontal electrode. The method was successfully applied to locate breakpoi

Rafael Silva Alipio

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Concrete Encased Grounding: Lightning Response Analysis Considering the Frequency Dependence of Soil

Assessment of the accuracy of the modal-domain line models with real and frequency-independent transformation matrix for electromagnetic transient simulation in lines with underbuilt cables

Closed-Form Expressions for the Calculation of the Ground-Return Impedance and Admittance of Underground Cables

Assessment of the Feasibility of Applying the Electromagnetic Time Reversal Theory to Locate Defects in Grounding Electrodes

Tower-foot grounding model for EMT programs based on transmission line theory and Marti's model

Probabilistic Load-Shedding Strategy for Frequency Regulation in Microgrids Under Uncertainties

High-frequency transients in buried insulated wires: Transmission line simulations and experimental validation

Importance of Ground Return Parameters in Transient Analysis of Overhead Wires

Small-argument analytical expressions for the calculation of the ground-return impedance and admittance of underground cables

Reliability of High-Frequency Earth Meters in Measuring Tower-Footing Resistance: Simulations and Experimental Validation

Assessment of the transmission line theory in the modeling of multiconductor underground cable systems for transient analysis using a full-wave FDTD method

A Comprehensive Analysis on the Influence of the Adopted Cumulative Peak Current Distribution in the Assessment of Overhead Lines Lightning Performance

An FDTD-Based Formulation for Solving the Transmission Line Equations for a Bare Wire Buried in a Dispersive Soil

Comparison of Different Formulations to Compute the Ground Return Parameters in the Analysis of High-Frequency Pulse Propagation Along a Wire Above a Lossy Ground

Assessment of the Transient Response of Wind Turbine Grounding Systems to Upward Negative Lightning

Assessment of the Transmission Line Theory in the Modeling of Multiconductor Underground Cable Systems for Transient Analysis Using a Full-Wave FDTD Method

On the Use the Electromagnetic Time Reversal Theory to Locate Breakpoints in Grounding Electrodes

An Overview of the Propagation and Surge Characteristics of Interconnected Wind Turbine Grounding Systems