Some aspects of overhead transmission lines lightning performance estimation in engineering practice

Abstract

Summary The paper presents some aspects of overhead transmission lines (OHL) modeling for lightning overvoltages estimation in engineering practice. Different models of elements are compared, and sensitivity analysis is performed with the aim to investigate their influence to the OHL insulation stress due to lightning discharges. Elements are modeled according to international technical documents covering this field. Great influence of applied model of air flashover to the lightning current, sufficient to cause back flashover, is noticed. Calculation results obtained with different combinations of element models have been compared and large deviations are noticed. The models of elements for lightning overvoltages estimation should be carefully chosen to achieve reliable estimations. Constant resistance model of tower grounding and voltage‐time curve model of air breakdown must be avoided in calculations, despite the fact that they are suggested in many technical documents dealing with lightning overvoltages at OHL. Copyright © 2015 John Wiley & Sons, Ltd.

Lightning protection of overhead transmission lines using external ground wires

“…Models of elements applied in simulations are used from the international technical documents [4,14,15] and in accordance with conclusions presented in [17].…”

“…A lightning strike is represented as a non-ideal current source consisting of an ideal current source with double ramp waveshape [15] parallel to the lightning channel surge impedance which is assumed to be 1000 [17]. Although there are some more accurate models of the lightning current waveshape, as Cigre source [14] or Heidler source [19], sensitivity analysis shows that, in the case when LPM model of air breakdown is used, the application of advanced lightning current models has small influence to the estimated results [17].…”

“…The minimum distance is determined so that there is a low probability of a flashover from the point of lightning strike at EGW to a protected OHL. The distance D is modeled as an air gap with a Leader Progression Model (LPM) flashover characteristic (1) [14][15][16][17] and this model is implemented in the EMTP-ATP program [6]: [16].…”

Reconsidering insulation coordination and simulation under the effect of pollution due to climate change

“…One major consequence of pollutants in such areas is the reduction of insulation or losing the insulation in transmission lines and stations. In such areas, an identification of an effective insulation in pollution scenarios is not only important for designing and selecting the appropriate type of insulation but also for adopting a proper maintenance plan of insulation devices . According to the literature, field visits, laboratory tests on insulators, computer simulation, and experience, there is a need for reconsidering insulation coordination in Mazandaran and Golestan power network.…”

“…Moreover, air gap estimation is based on calculations of power frequency voltage, lightning, and the switching conditions in the area. In general, insulation calculations included 4 phases of calculating pollution, lightning overvoltage, switching overvoltage, and frequency of power overvoltage . The calculations are summed up in the 2 measures of insulator chain distance and the required air gap.…”