Detection of metallic turn-turn short circuit of dry air core reactor based on digital twin current method

For the sake of obtaining current distribution characteristics of dry-type air-core reactor under normal functioning and turn-to-turn short circuit fault, the equivalent circuit of the turn to turn insulation fault is established, and the calculation formula of the equivalent impedance and current under voltage source or current source are given. The equivalent circuit and coil parameters of dry-type air-core reactor excited by voltage source are simulated by finite element method; The equivalent circuit and coil parameters of dry-type air-core reactor excited by current source are calculated analytically and verified by experiments. The feature: with the change of reactor excitation mode, dry-type air-core reactor presents different current distribution characteristics is showed by the results; With the change of the position of the short circuit turn, different distribution characteristics are presented by the current in each layer of the dry-type air-core reactor, and certain distribution characteristics with the change of the position of the short circuit turn are presented by the current in the same layer. Based on this, a method for monitoring and locating the inter turn short circuit fault of the dry-type air core reactor under multiple-harmonic excitation is proposed. It is suggested to select current as the monitoring parameter of turn-to-turn insulation of dry-type air-core reactor, the results can be used in the digital twin technology of power equipment monitoring, which is of great significance to realize the intelligence of power equipment condition evaluation.