Horacio Torres

Calculation of Lightning-Induced Voltages on Overhead Distribution Lines Including Insulation Breakdown

This paper investigates the influence of considering actual insulation volt-time curves both in the calculation of lightning-induced voltages and in the estimation of the number of flashovers an overhead wire may experience per year due to nearby lightning strokes. The flashover mechanism is modeled according with the integration method, which is used as a reference for comparisons with the simplified 1.5 CFO flashover criterion traditionally used in the estimation of the lightning performance of overhead distribution lines. Sensitivity analysis show the dependence of flashovers on the shape and front time of the assumed channel-base current. The obtained results suggest that the simplified 1.5 CFO flashover criterion is likely to underestimate the number of flashovers an overhead line may experience per year due to nearby lightning strokes. This result is confirmed by statistical analyses considering a Monte Carlo-based approach. It is also shown that more realistic flashover rate estimates can be obtained in the statistical analysis of lightning-induced voltages provided a reduced threshold level (1.2 CFO in the particular case evaluated in this paper) is considered instead of the 1.5 CFO level traditionally used in this type of study.

Evaluation of Lightning-Induced Voltages Over a Lossy Ground by the Hybrid Electromagnetic Model

In this paper, the hybrid electromagnetic model is applied to calculate lightning-induced voltages over a lossy ground. Results provided by this model are compared with experimental data obtained from a reduced-scale model and with results simulated by the numerical electromagnetics code. Good agreement is achieved in all cases.

Optimizing the Surge Arresters Location for Improving Lightning Induced Voltage Performance of Distribution Network

This paper will deal with improvement of lightning induced voltage performance of distribution network by optimizing the surge arrester location on the distribution network. The optimization of the location is made by using a novel formulation based on genetic algorithms. Here is described the implementation of this methodology by using sophisticate software which has been used for lightning induced voltage analysis. It is also described the capabilities and the limitations of this novel formulation. The performance of the network is evaluated by means of a probability distribution curve obtained from a statistical evaluation of the lightning induced voltages on the distribution line.

Contribution to Lightning Parameters Study Based on Some American Tropical Regions Observations

This paper presents a recent characterization review of three cloud-to-ground lightning parameters [lightning peak current, ground flash density, and keraunic level (KL)] used in engineering applications based on available data from studies conducted in some tropical countries of Central and South America (Brazil, Colombia, Costa Rica, and Venezuela), considering seasonal and spatial variation aspects. There are some differences between the behaviors of the analyzed parameters in tropical areas in comparison with those published in the literature for temperate ones. The most significant conclusion is that historical data suggest that the highest ground flash density are located between latitude of 8° and 10° north. This value is much higher than the highest values reported for countries located in temperate regions. It is seen from the KL analysis that this parameter varies depending on the latitude with values up to 200 thunderstorm days (TDs).

A methodological proposal for monitoring, analyzing and Estimating Power Quality indices: the case of Bogotá-Colombia

The estimation of power quality (PQ) indices has a vital importance on the development of national PQ standards not only because provides truthful information about PQ conditions in our facilities, but also because permits to establish, with an own criterion, the values for the limits of the most common PQ disturbances. This paper proposes a methodology for the estimation of PQ indices based on statistical sampling and weighting factors techniques which are applied for commercial and industrial customers in the city of Bogota. In addition, some strategies for the classification of the type of customer as well as some final obtained values of PQ indices in Bogota are presented.

Sensitivity analysis of induced voltages on distribution lines

This paper presents a sensitivity analysis of induced voltages on overhead distribution lines due to some lightning and line configuration parameters variations. The sensitivity analysis was made initially varying just one parameter individually and then was varied whole parameters at the same time analyzed by means of nonlinear regression models. This analysis shows the parameters that have more influence on the induced voltages. It was also obtained an approximate equation to calculate the maximum induced voltage along the line. The obtained equation was also compared with other approximate equations such as Rusck and Jankov.

Impact Assessment of Power Quality Limits in Colombia: a Regulatory Approach

In order to improve present regulations about power quality (PQ) in Colombia, an impact assessment of PQ limits among utility companies and customers is presented in this paper. This evaluation takes into account results obtained from a previous project of PQ measurements in Bogota-Colombia (PQB) over a representative sample of end users. This paper evaluates the percentage of users that would be surpassing some proposed limits for PQ disturbances such as: THD, TDD, individual harmonics, unbalance voltage, flicker and unbalance current. This analysis was carried out for industrial and commercial facilities taking into account that these users require higher levels of power quality and therefore may inquire in bigger costs in case of poor power quality conditions compared to other type of users such as residential customers. The results achieved in this work show that for some disturbances is possible to apply a regulation based on international standards as IEC and IEEE but in other parameters their application could become very expensive for utilities and end users

Implementation of Genetic Algorithms in ATP for Optimal Allocation and Sizing of Active Power Line Conditioners

In last years optimal allocation of active power line conditioner (APLC) at industrial facilities has become an important research subject. In this work the genetic algorithms (GA) are used to determine the allocation and sizing of APLCs. This methodology is implemented in ATP (alternative transients program), and particularly with its components called ATP models routines. The main topic of the paper is to illustrate the process used to achieve the implementation of GA with these components using ATP foreign functions. The structure of chromosome, the genetic operators and a novel concept of ATP models networks are described. The approach proposed is applied on an 11 bus test system, illustrating the minimization of voltage distortion at PCC (point coupling common) and the current harmonic injection of APLCs

Statistical evaluation of transferred voltages through transformers due to lightning induced overvoltages

This paper deals with the evaluation of the transferred voltages to the transformer low voltage side, due to lightning induced voltages on overhead distribution lines. The induced voltages calculations, taking into account the presence of electrical devices connected to the electric networks like transformers and surge arresters, is done by its implementation into the ATP/EMTP program. The frequency of certain voltage to be exceeded is evaluated using the Monte Carlo method in order to generate multiple simulation parameters randomly. As a result, it is shown that in some cases the protection devices used to attenuate the overvoltages are insufficient from the users point of view.

A Status Report on Colombian Distributed Generation

This paper presents the Colombian distributed generation status as a first approach for establishing the interconnection requirements of small-scale generators in the Colombian distribution systems. A national and international standard bibliographical review about this topic was made, and the distributed generation technologies available now were identified. This topic has not been explored widely in this country; however, it is becoming an interest area for the regulators entities, because it is considered a great alternative for the electric power supply in Colombia.