Single-phase Adaptive Reclosure for EHV and UHV Transmission Lines with Shunt Reactors

The present single-phase reclosure normally using a fixed reclosure time may aggravate potential damage to system and equipments in the case of a permanent fault and insufficient transient fault. Thus, it is important to research on the single-phase adaptive reclosure (SPAR) technique aiming to distinguish permanent and transient faults for extra-high-voltage (EHV) and ultra-high-voltage (UHV) transmission lines. Based on the comprehensive analysis of the characteristics of the current from the shunt reactor and the recovery voltage in the open phase, a practical single-phase permanent fault identification scheme is developed, which employs beat-frequency characteristics of the shunt reactor current and voltage in the open phase. As for the primary criterion using the current with high measurement precision, the current-based criterion is more reliable than the voltage-based criterion under a relatively lower shunt reactor compensation rate. Besides, the voltage-based backup criterion is helpful to improve the reliability of the permanent fault identification, which can avoid wrong identification for some transient faults with subtle beat frequency character in the shunt reactor current. ATP simulation results show that the proposed scheme is correct and effective, which provides a simple and practical method for the realization SPAR in EHV and UHV transmission lines.