Leakage Flux based Turn-To-Turn Fault Detection for Shunt Inductor

Dry-type iron-core inductors in urban high-voltage substation reactive power local balance and reasonable control of voltage fluctuations plays an important role [1]. As its number of applications and uptime increase, the amount of failure must also increase. The most common events of dry-coil devices are interturn faults, which can damage the insulation of the coil and even burn the device when a large current generated in the short-circuit loop. Right now, the low-voltage dry-type iron-core inductors lack a special inter-turn fault detection method and generally use overcurrent protection and temperature detection protection. The zero-sequence and negative-sequence power direction protection are mostly used for ultrahigh-voltage inductors protection [2]– [3]. Therefore, this paper proposes to use the difference of the distribution characteristics of space magnetic field in normal operation and inter-turn fault as the criterion of on-line detection algorithm for turn-to-turn fault [4]–[5]. In this paper, a field-circuit coupled finite element model of a three-phase iron-core inductor is established. The distribution characteristics of the spatial magnetic field under normal operating conditions and different inter-turn fault conditions are simulated and analyzed. This result provides a theoretical basis for the inductor on-line detection algorithm of non-contact turn-to-turn fault.