Magnetizing Current Harmonics Mitigation for Enhanced PMSG Operation Under Grid Voltage Imbalance

When a Permanent Magnet Synchronous Generator (PMSG) is linked to the utility grid and operating under imbalanced voltage conditions, apart from facilitating power control, the controller must be enforced to limit the grid current THD while mitigating the harmonics in power, torque, DC link voltage, etc. A negative sequence magnetizing current harmonics mitigation scheme using modified negative sequence compensating stator reference currents for PMSG is proposed here. Machine Side Converter (MSC) is employed to extract desired power from PMSG while compensating the magnetizing current harmonics resulting in the minimization of power and torque ripples and regulates the DC link voltage. Grid Side Converter (GSC) maintains Unity Power Factor (UPF) at the grid terminals. A single control target of mitigating the magnetizing current harmonics can facilitate simultaneous mitigation of torque, power and DC link voltage ripples while maintaining sinusoidal and balanced grid currents. The efficacy of this scheme is verified in PSCAD/EMTDC for a 2.5kW laboratory PMSG test setup.