Lightning surge into a substation at a back-flashover and review of lightning protective level through the FDTD simulation

Abstract

Higher accuracy in the lightning-surge analysis has been pursued; based on circuit analysis. However, the need to analyze phenomena where a plane wave propagation mode cannot be assumed is an outstanding issue. The finite-difference time-domain (FDTD) method is a dominant measure to solve such issue. This study evaluated surge waveforms intruding into a 500 kV air-insulated substation due to a back-flashover through FDTD simulation. The lightning surges were calculated with the inclined angle of the incoming line changed from 0 to 69 degrees and the voltage of the lightning surge intruding into the substation decreased with increasing incline angle of the incoming line. At the open end of the incoming line to the substation at the circuit breaker, the voltage was minimized and maximized when the span length was 20 m and 200 m respectively. This result differed in terms of characteristics from that obtained using the conventional circuit analysis model, whereby the voltage was minimized when the span length was 200 m. The lightning overvoltage at the circuit breaker terminal based on FDTD analysis was lower than that based on circuit analysis. Their relative ratio is 0.557 for a standard incoming line span length of 150 m, showing a 44 % reduction in FDTD analysis from the circuit analytical result. Since the current lightning impulse test voltage is evaluated based on this circuit analytical result, it was clarified that the lightning impulse test voltage level could be potentially reduced with consideration of the inclined conductors at the incoming line span, the vertical conductors of the tower and lightning path, and their mutual coupling with the transmission line. Index Terms -Transmission line, substation, incoming line, lightning surge, backflashover, non-uniform line, lightning protection design.

FDTD-Based Lightning Surge Simulation of an HV Air-Insulated Substation With Back-Flashover Phenomena

“…Substituting (13) and J n +1/2 z = I n +1/2 L /Δs 2 into (14), we can obtain the following equation to update the electric field across the flashover model:…”

“…In addition, to apply the FDTD method to lightning surge analysis with nonlinear phenomena, several techniques have been developed to represent lightning surge arresters [9], [10] and flashover phenomena at a long air gap such as arcing horns in high-voltage transmission lines for FDTDbased surge simulations [11] by employing a flashover model developed for circuit-theory-based simulations [12]. The technique used to represent long-air-gap arcing horns in the FDTD method was employed in lightning surge analyses of a 500-kV air-insulated substation [13], [14] and a 275-kV transmission line [15].…”

“…Second, they can model nonhorizontal wires, such as incoming power lines to substations and lightning channels, straightforwardly and take into account the electromagnetic coupling between different wires and between wires and lightning channels in a 3-D arrangement. To clarify this point, in [13], [14], [18], lightning surges invading a 500-kV air-insulated substation were calculated using the FDTD method and the calculated results were compared with those obtained by the circuit-theorybased simulation program, EMTP (electromagnetic transients program). The FDTD simulations showed that the lightning overvoltage decreases when the inclination of incoming power lines to the substation is increased, that is, the span between the first transmission line tower and the substation is smaller, while the circuit-theory-based simulations showed the opposite trend to that in the FDTD results.…”

Three-Dimensional FDTD-Based Simulation of Lightning-Induced Surges in Secondary Circuits With Shielded Control Cables Over Grounding Grids in Substations

“…In previous studies regarding the application of the FDTD method to the lightning transient analysis of substations, the main focus was put on the analysis of lightning transients entering substations owing to lightning strikes and of the transient responses of grounding structures (e.g., [31], [37], [38], [39], and [40]). Such lightning transients propagate in the primary circuits and the grounding structure of substations, and then electromagnetic disturbances are induced in the secondary circuits through the effect of surge transitions from the primary to secondary circuits at instrument transformers such as VTs and CTs, the effect of transient ground potential rises (GPRs) of the grounding structure and electromagnetic coupling due to the lightning currents propagating through the grounding structure, the effect of direct coupling from the lightning transients propagating through the primary circuits, and so forth [20].…”

A New Thunderstorm Identification Algorithm Based on Total Lightning Activity

“…Thunderstorms have a severe impact on many sectors, such as agriculture, aviation, infrastructures and power systems (Houston et al., 2015). Lightning caused by thunderstorms (Hayward et al., 2020) is responsible for damages and interruptions of power system (Li et al., 2013; Okabe & Takami, 2011; Perez et al., 2020; Takami et al., 2014; Visacro et al., 2012). Although there are many kinds of lightning protection equipment in power system (Hu et al., 2021), severe damage caused by lightning is one of the biggest threat in operation (Guo et al., 2019), especially devices in bulk power transmission schemes (Goertz et al., 2018; Zhuang et al., 2016).…”