Research on current imbalance law of bus - bar caused by inter - turn short circuit of dry-type air - core reactor

Abstract

Dry-type Air-core Reactor is widely used in power system. It is an important reactive power compensation equipment in power system. In recent years, the dry air reactor has suffered a number of failures in operation. The failure occurred most frequently in the dry-type air-core reactor and we cannot detect the inter-turn short circuit faults in neither single wire winding nor multiple wire windings. The research and protection of reactor faults is almost in the blank at present. This paper presents the method of collecting the unbalanced current between bus-bars to detect the winding inter-turn short circuit faults. The numerical simulation of short circuit model between different windings of the reactor is carried out. Current-differential analyzed on the unbalanced current data of experiment are used to determine whether an inter-turn short circuit occurs. The results indicated that the closer the short-circuit is to the end of the reactor, the greater the unbalance current is. The changes of collecting current between bus-bars are much larger than the total current. Short-circuit current redistribution only occurs between two windings after the short circuit. The circuit in other windings is almost unchanged.