A new adaptive single phase auto-reclosure scheme for EHV transmission lines

Almost 70-90 % of faults in extra high voltage (EHV) transmission lines in modern interconnected power systems are intrinsically transient. The necessity of rapid fault clearing results in fast developing of protection equipments. Morever, need for reliable supplying of loads, lead to improve in single phase auto-reclosing equipments. In this paper, a new method is proposed to reduce dead time of transmission lines. Leads to improve the performance and efficiency of single phase auto-reclosing. In the occurrence of permanent faults, the proposed yardstick is accurate and authentic to diagnose fault's type (transient or permanent). To validate accuracy and authenticity of proposed method, a 765 kV transmission system is simulated in Electromagnetic Transients Program Software and results are presented.

I. Introduction

NEARLY, 80 % of faults in EHV transmission lines are intrinsically transient [1]. The most prevalent potential of transient faults is lightning, transmission lines switching and jiff contact by external objects. This transient faults can be cleared by temporary opening the faulted phase. So, these faults are allowed to be self-cleared. For this type of faults, transmission system can be energized by Single Phase Auto-Reclosing (SPAR). This strategy improves reliability and stability of power system [2]. These types of faults include permanent faults which are not clearable by auto-reclosing. Wire's scrapping which cause that permanent fault is happened, can incur system and utilizes. The conventional auto-reclosing is not recommended especially in transmission lines located near generators [3]–[5]. Therefore, locking of auto-reclosing equipment is attended in last decade.