Luiz H. Meyer

Study of the correlation between weather conditions and protection trips in a 230 kV transmission line in southern Brazil

This paper presents a study of investigation of possible correlation between weather conditions and protection trips of a 230 kV transmission line in southern Brazil. This transmission line has a history of outages during winter, ever since its initial operation in 1974. Most of these outages are caused by single phase faults randomly located along the line. In consequence, many studies have been done to identify the main reason for these events, including now the investigation of the influence of the relative humidity of the air, rainfall index and wind direction in this region to justify these problems that affect the reliability of the protection systems of this transmission line. Thus, preliminary results shown in this work allows to identify a correlation between faults and local weather conditions.

Methodologies for implementing improvements in maintenance of power transmission lines

This article describes and analyzes the historical incidence of defects along overhead power transmission lines over the area of the state utility company CEEE-GT, in Southern Brazil in order to suggest improvements for the program of maintenance of this company that may applicable to several other similar companies. To this end, two methods are presented: the first one classifies the defects in accordance with their risks to system functionality, in view of establishing a guideline for the corrective maintenance program. The second method establishes the frequency with which rigid detailed inspections should be done in accordance with historical incidence of defects along the power transmission line.

A tool for analysis of fault location in transmission lines based in estimated transients

This paper presents a tool based on MATLAB™ program that has been devised to reproduce the observed and simulated transients of the high voltage (HV) power system network on the ATP program. The graphical interface can to help in the interpretation of high frequency travelling waves. Therefore, the analysis of these transients can be used to assist in the fault location in transmission lines. The practicality of this tool is demonstrated applying a methodology for estimating voltage transients from current transients, based on the properties travelling waves instigated on transmission line as a result of a fault. The application of this analysis tool will be demonstrated through some simulated cases on the CEEE-GT 230 kV transmission system of Brazilian power system.

An analysis of the performance of power circuit breakers using a non-invasive system

Some researches have shown that arcing produces impulsive radio-frequency radiation and through timing analysis of the received and recorded impulses, the switching times of circuit breakers can be measured and utilized in order to ensure the safe operation and reliability of these equipments. In this context, this paper presents a performance evaluation of power circuit breakers (CBs) using an antennas-based system along with signal processing techniques. The signals obtained from the arc created during the switching process are captured by the antennas and then processed aiming to characterize the operation process of the CB. Results of this analysis are shown for field measurements performed on CBs attached to shunt reactor of a substation in the southern Brazil.

Coupling Transmission Lines for Wave-Shape Adjust in High-Voltage Surge Tests

High-voltage (HV) tests are usually required for evaluating electrical withstand of equipment, such as power transformers. These tests are based on standards that suggest values for the parameters of the voltage surge wave shape to be applied. However, for the personnel of HV laboratory, the adjustment of the wave shape is not an easy task. Although standards usually have some flexibility for the parameters of the wave shape for some transformers, it may be even impossible to reach any wave shape that may be minimally acceptable. Based on this problem, this paper presents a conceptual solution that is a special coaxial transmission line to be inserted between the equipment and the impulse generator. The proposed line has a special design in view of matching properties of the impulse generator and the equipment to be tested. Simulation results from the proposed configuration are presented with a discussion of its theoretical performance.

An analysis of the performance of surge suppression devices applying the TLM method

This work presents an analysis of the performance of surge suppression devices that currently are applied in power distribution network. Based on the Transmission Lines Method - TLM, numerical models for these devices have been created and their computational implementation made by using MATLAB™ codes. These models were simulated with some types of power surges and a comparison of results is made with measurements of actual devices and other methods of simulation obtained in the literature for verifying the efficiency of the proposed methodology. Also, it is presented some advantages over other methods for analysis of power distribution network, subjected to the effects of fast transients.

An analysis of the overvoltage in the secondary network, considering a transient grounding resistance.

This work presents an analysis of the overvoltage in the secondary network caused by lightning discharges that are transferred from the primary through the transformer. Numerical simulations using TLM- Transmission Line Modeling and ATP- Alternative Transients Program are presented to show and to establish comparisons between two models for the grounding resistance of the transformer and customer: the traditional model with constant resistance and the model proposed in this work, considering a transient resistance.

Analysis of the overvoltage in the power distribution networks using two models of the grounding resistance: The traditional model with constant resistance and considering a transient resistance

This work presents an analysis of the overvoltage in the distribution network caused by lightning discharges. Numerical simulations using TLM- Transmission Line Modeling and ATP- Alternative Transients Program are presented to show and to establish comparisons between two models for the grounding resistance of the transformer and customer: the traditional model with constant resistance and considering a transient resistance.