Secondary Arc Extinguishing During a Single-Phase Fault at the Long High Voltage Overhead Lines - Case Study of a Real Power Network

Abstract

AbstractA power system design is determined by transient conditions, rather than by steady state behavior, hence the significant attention is payed to the analysis of transients in long overhead lines (OHLs). There is an attempt to reduce the secondary arc current magnitude and the extinction time that is created by the stray and ground capacitance in these long lines. The usual concept in solving these problems is by using line shunt reactors (SR) that are grounded by neutral grounding reactors (NGRs). This paper analyzes the performance of proposed SRs and NGRs with an example of a real high voltage transmission power system operating in Tanzania, investigates the overvoltages during the single-phase to ground fault, secondary arc current magnitude and the extinction time. The analyzed quantities are important for further power system protection settings parameters, since the successful single-phase autoreclosing (SPAR) strictly depends on the arc extinction time. It is intended to reduce this time in order to enable fast SPAR to prevent the system instability while ensuring that the equipment will withstand the caused stresses. It is shown that the implementing such reactors and NGRs would be beneficial in terms of reducing the secondary arc current, and extinction time. The caused overvoltages does not negatively affect the other equipments’ performance in terms of stress. Besides, such configuration will help the power system during the normal operation, not only during the fault, since the inductive load, such as the shunt reactors, have other benefits in long OHLs. Moreover, this paper provides a strong base for the further analysis of similar phenomena, that can be translated to other models, i.e. network conditions and transients with the SPAR implementation, shunt reactors switching transients, surge arresters performance etc. All the analysis have been performed by applying PSSE and EMTP-RV professional software tools.KeywordsShunt reactorsSecondary arcNeutral grounding reactorsTransients