Vibration-Based Rotor-Side-Converter Open-Switch-Fault Detection in DFIGs for Wind Turbines

Due to the strong growth of wind power in the energy mix and the intense development of higher-power wind turbines, reducing the operating and maintenance costs has become a crucial aspect nowadays to guarantee the security of electricity supply. Condition monitoring plays a key role in achieving this goal. Today most monitoring strategies for converters focus on monitoring the electrical parameters of the converter and on temperature monitoring of the insulated-gate bipolar transistors (IGBTs) in a direct or more indirect way. This paper proposes an alternative approach. Vibration measurements performed on the doubly fed induction generator (DFIG) connected to the converter are used to detect the converter IGBT problems. We focus on the open-switch fault in the rotor side converter (RSC) to illustrate this concept. Spectral analysis is done on the measured vibrations to detect this type of faults. First, the approach is illustrated by means of a simulation model representing a 3 kW DFIG wind turbine test bench. In a second step, the approach is validated on the corresponding bench. A differentiation is made between sub-synchronous and super-synchronous rotation speeds. The ability of the method to detect the fault in both conditions is shown.