Anto Joseph, Thanga Raj Chelliah, Raghu Selvaraj, and Kyo-Beum Lee, "Fault Diagnosis and Fault-Tolerant Control of Megawatt Power Electronic Converter-Fed Large-Rated Asynchronous Hydrogenerator," IEEE Journal of Emerging and Selected Topics in Power Elec > Paper

In recent years, it has been difficult to achieve power converter redundancy in multi-channel voltage-source inverter (VSI)-fed large

rated doubly fed induction machines (DFIMs), and it has not yet been adopted in any commissioned variable-speed pumped storage

power plants. Multi-channel VSIs are a fundamental part of DFIMs, and they control the real and reactive power of the machines.

This paper presents the fault-tolerant operation of a large rated DFIM hydro-generating unit at open switch faults in back-to-back

VSIs. A technique for diagnosing the open-switch faults in grid-side and machine-side converters is proposed. An open-switch fault

is detected based on the variation in rotor currents and dc link voltage, which reduces the computational efforts during fault

diagnosis. A 250-MW DFIM with five-channel three-level VSIs (each rated at 9 MVA) is simulated in the Matlab/Simulink environment

to observe the drive behavior. Finally, a 2.2-kW DFIM is tested in a laboratory environment to verify the simulation results.