Experimental research and analysis on rotor winding inter-turn short circuit fault in DFIG

Abstract

Nowadays harnessing electric power wind is one of the most important forms of sustainable power production. A doubly-fed induction generator (DFIG) has been commonly used in wind turbines. DFIG has been affected negatively by the short circuit fault of rotor windings, so it is core important to examine doubly-fed induction generator for safe and continuous operation of the wind turbine. For this purpose, an experiment has been setup to detect inter-turn short circuit faults in rotor phase. Experimental setup with a 380 V, 50 Hz, 4-pole 100 kW three-phase wound rotor induction machine has been used to get the real experimental data. Three phase rotor currents are measured to detect the inter-turn short circuit fault. Root mean square (RMS) value of rotor currents, ratio between negative to positive sequence of current and phase difference are used to analyze the faults. The RMS value of the rotor three phase current increases as the fault grows. When the inter-turn short circuit fault occurs the negative sequence of current appears and ratio between negative to positive sequence of current also increases with the fault level. The phase difference of Phi-ca increases as the fault degrees increases and the other two phase difference (Phi-ab and Phi-bc) decreases. The proposed paper is of great importance in the field of the condition monitoring of wind turbine as it is based on the real experimental results.