Analytical Expressions for Lightning Electromagnetic Fields With Arbitrary Channel-Base Current. Part II: Validation and Computational Performance (original) (raw)
Related papers
Numerical electromagnetic analysis of lightning-induced voltage over ground of finite conductivity
IEEE Transactions on Electromagnetic Compatibility, 2003
The electromagnetic transients of lightning protection system(LPS) under direct lightning strike is studied using NEC2. By employing antenna return-stroke model, lightning channel's inducing effect and finite conductivity of ground are all taken into account. Results show that the lightning channel's inducing effect tends to decrease the current flowing through horizontal conductors, and increases the current flowing through vertical conductors near the striking point. The results obtained under perfect ground assumption have a good agreement with the published experimental results. The simulation also predicts that the finite conductivity of the ground affects the branch current significantly, it increase the LPS's current dissipating efficiency, the higher the soil resistivity, the more uniform the current flowing in vertical conductors.
Lightning Electromagnetic Fields Computation: A Review of the Available Approaches
Energies
Lightning represents one of the most critical issues for electrical infrastructure. In dealing with overhead distribution line systems, indirect lightning strikes can lead to induced voltages overcoming the critical flashover value of the line, thus damaging the insulators. The computation of lightning-induced voltages requires the modeling of the lightning current, the evaluation of the lightning electromagnetic fields and the solution of the field-to-line coupling equations. The numerical calculation of the lightning electromagnetic fields is time-consuming and is strongly dependent on the lightning channel modeling and soil properties. This article presents a review of the most widely adopted methods to calculate the lightning electromagnetic fields, starting from the classical formulation, which requires numerical integration, and highlighting the most effective approaches that have been developed to reduce computational effort. This is done first for the case of a perfectly con...
Procceedings of the International Conference on Power Systems Transients (IPST-2005), 2005
Abstract—Lightning-induced voltages are important sources of power quality problems: indeed, they can cause short interruptions and voltages sags on distribution systems. The analysis of these disturbances induced on distribution networks by lightning electromagnetic pulses (LEMP) radiated by nearby lightning, requires the availability of accurate models and relevant computer programs of LEMP-illuminated lines. These should be able to reproduce the real and complex configuration of distribution systems including the presence of ...
Evaluation of Lightning-Induced Voltages Over a Lossy Ground by the Hybrid Electromagnetic Model
IEEE Transactions on Electromagnetic Compatibility, 2009
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.
IEEE Transactions on Electromagnetic Compatibility, 2021
The paper provides analytical expressions for the electromagnetic fields generated by a lightning return stroke characterized by a channel base current with arbitrary time waveform, in presence of either a perfectly conducting or a lossy ground, assuming the transmission line model for the current along the channel. In this second case, a time domain analytical expression for the Cooray-Rubinstein formula is presented. The main idea that leads to the derivation of analytical formulas consists of dividing the channel into intervals in which the distance between the field source point and the observation point can be approximated with a linear function of the time and of the spatial coordinates of both points. In the companion paper, a detailed comparison is proposed with the classical (numerical) approach highlighting excellent agreement both at close and far distances, considering all the values of practical interest for the ground conductivity. Moreover, the method guarantees a meaningful improvement in the computational performance.
Journal of Electrostatics, 2004
In the present paper, transient-induced voltages on a distribution line over finitely conducting ground, which are associated with lightning to a 200-m high stack, have been analyzed by Numerical Electromagnetics Code (NEC-2). An electromagnetic model (EM) of a lightning channel, which contains additional distributed inductance to simulate the reduced propagation velocity of lightning current, has been employed. Validity of the employed model which incorporates a tall structure and a lightning channel has been discussed by comparing calculation with measurements. r
An Exact Closed-Form Solution for Lightning-Induced Overvoltages Calculations
IEEE Transactions on Power Delivery, 2009
We present the evaluation of the induced voltages in a lossless single transmission line, located at a given height over an infinite conductivity ground plane, and exited by an external field due to a step current moving along a vertical channel. This is a classic topic of the theory of lightning-induced voltages on power lines. The technical literature related to this topic has performed a significant effort; however, only approximated formulas have been obtained so far. In this paper, we derive the exact closed-form solution. We also will discuss, evaluate, and compare the approximated formulas with reference to the proposed exact one, thus contributing to clarifying a matter that still is debated and sometimes misleading, as we will show in the paper. We furthermore recall that the examined lightning-induced voltages model is fundamental for the IEEE standard 1410, a guide for improving the lightning performance of power distribution line.
IEEE Transactions on Electromagnetic Compatibility, 2000
This paper presents the calculation of lightninginduced voltages over lossy ground, generated by a lightning strike to a flat ground and a tall object. A hybrid electromagnetic circuit model method adopting an approximation formula, i.e., Cooray-Rubinstein expression, is employed in this paper. A comparison of the simulation results with experimental data shows that the Cooray-Rubinstein formula is still good enough for the calculation of a lightning-induced voltage. Electric fields calculated by the proposed method, and by equations derived by Master and Uman and a conventional dipole technique, are compared. The two approaches yield the same total electrical fields but different components of electrostatic, induction and radiation.