Lightning characterization for flashover rate calculation of overhead transmission lines

Lightning performance analysis of transmission lines using the Monte Carlo method and parallel computing

“…The approach applied here was used to obtain a line model in which corona could introduce a steepness variation close to that recommended in equation (3); the goal is to have a line model that could be used for estimating the incoming surge [1]. • The BFOR is sensitive to the coefficient of correlation between the peak current magnitude and the rise time, although the SFFOR is not; consequently, the LFOR decreases as the coefficient of correlation increases; see [3] and [10]. In other words, accurate knowledge of this coefficient is an essential issue for flashover rate calculations.…”

“…Not only the incidence model but other aspects needed to obtain the LFOR of an overhead transmission line have been simplified. See [3], [10] and [28] for other aspects that could have been considered in this work.…”

“…Return stroke parameters: Although negative flashes have multiple strokes, only the first and the second strokes are of concern for transmission insulation levels; that is, peak current magnitudes of the third and the subsequent strokes are much lower than those of the previous strokes and they do not represent a threat to transmission lines. Actually, only an accurate knowledge of the parameters of the first negative stroke can be crucial for transmission lines with rated voltage 400 kV and above [10].…”

“…A return stroke is repre-sented by a concave waveform (see Figure 1), with parameter n = 3.24 in equations (2a) and (3). • Footing resistances are represented as nonlinear resistances modelled according to equation (7) with R o = 20 W. The value of the soil resistivity r is 100 ohm-m. • Insulator strings are represented by means of a simple model (implemented in ATP MODELS language) that duplicate a time-lag curve (see Figure 3) The length of insulator strings is 5.6 m. Assuming the critical flashover voltage (CFO) of insulator strings for negative polarity strokes is estimated as [20] CFO − = 700 ⋅ d s (10) where d S is the striking distance of insulator strings, the corresponding CFOis 3920 kV [3].…”

Emtp Implementation of a Monte Carlo Method for Lightning Performance Analysis of Transmission Lines

“…Such procedure may consist of the following steps: generation of random numbers to obtain those parameters of the lightning stroke and the overhead line of random nature; application of an incidence model to deduce the point of impact of every lightning stroke; calculation of the overvoltage generated by each stroke, depending on the point of impact; calculation of the ashover rate [6]. This paper is aimed at detailing the main computational aspects of the procedure and models developed by the authors for assessment of the lightning performance of overhead transmission lines [6][7][8][9]. A Monte Carlo procedure and new models for representing several parts of a transmission line in lightning overvoltage calculations have been implemented in the ATP package.…”