Mathematical Modeling of Arc Faults in Networks with Low Single Phase-to-Ground Fault Currents

Andrei Brilinskii,Irina Ryndina,Anna Petrova,Georgiy Evdokunin,N Vatin,E Vdovin,P Zunino

doi:10.1051/e3sconf/201914005001

Andrei Brilinskii, Irina Ryndina + Show 5 more

Open Access

https://doi.org/10.1051/e3sconf/201914005001

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Abstract

The article comprises the results of the research defining open-flame arcs self-quenching conditions in the event of a single phase-to-ground fault in overhead medium-voltage distribution networks according to existing theories of arc extinguishing. The calculations included metallic and arc faults modeling in a network with low phase-to-ground fault current. The arc gap simulation based on the mathematical channel model of a cylindrically symmetrical upright arc stabilized by rising convective gas flow was carried out in ATPDraw software program. The single phase-to-ground arc fault calculations results indicated an increase in high-frequency currents’ attenuation rate during transient processes as well as a reduce reduction in the electric arc lifetime from 8 ms to 2 ms in case of the breakdown voltage decrease from the peak value to zero. Notably, in case of low single phase-to-ground fault current the arc extinguishing took place at the first high-frequency current zero. For the cases of nonzero breakdown voltages, the electric arc extinguishing was detected at the fundamental frequency current component zero-crossing instant. The maximum overvoltage ratio of K = 2.8 was obtained as athe result of the single phase-to-ground fault at the peak phase voltage.

Highlights

The chief advantage of insulated neutral distribution systems lies in the network line voltage continuity in case of a single metallic phase-to-ground fault, steady supply of the customers can be carried out in practice [1]
A metallic single phase-to-ground fault at the instant of peak phase voltage t1 = 40 ms was under consideration first
At the initial instant after the single phase-to-ground fault occurred the voltages to ground of the healthy phases rose, the overvoltage rate approached to the value of K = 2.74

Summary

Introduction

The chief advantage of insulated neutral distribution systems lies in the network line voltage continuity in case of a single metallic phase-to-ground fault, steady supply of the customers can be carried out in practice [1]. Namely electric arc faults, various arcing modes can take place that directly depend on the fault current, and the arc plasma gap deionization conditions. A stable arc existence is possible if the fault current is high as long as the gap is not able to deionize significantly during the current zero-crossing. Reliable and safe network operation requires such a ground-fault current value that fault development possibility remains neglectable continuously. In compliance with [2] for 6, 10, 35 kV electric power networks in Russian Federation the upper-range values of phase-to-ground fault current are 30, 20, 10 A respectively. The rated ground-fault current values are slated to provide arc self-quenching or promote successful reclosing of the faulted line if available

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Conclusion