Low Harmonic Modular Multi-level Converter Integration in Doubly Fed Induction Motor for Wind Energy Applications

The Doubly Fed Induction Motor (DFIM) is essential in Wind Energy Conversion Systems (WECS) for efficient wind energy harvesting. Conventional power converters in WECS often result in high Total Harmonic Distortion (THD) in output voltage and current, affecting wind energy economy. This research proposes replacing conventional converters with Modular Multi-level Converters (MMC) due to their scalable topology, low harmonic distortion, high efficiency, and the elimination of DC link capacitors. The MMC is connected in a back-to-back configuration between the rotor of the DFIM and the grid to enable four-quadrant operation. Circulating current in the MMC is minimized using a Modified Deer Hunting Optimization (MDHO) based Fractional Order PID (FOPID) controller and a Mexican Axolotl Optimization (MAO) based FOPID. Capacitor voltage balancing is achieved using Level-Shifting PWM (LSPWM) and Three-Dimensional Space Vector PWM (3D-SVPWM) techniques with voltage sorting algorithms. The impact of these control and modulation techniques on the DFIM is analyzed in terms of reduced THD, and steady state and transient performance. Simulations are conducted in MATLAB/R2022a, and experimental validation is performed using a 7-level 0.5 kW MMC in a Hardware-In-Loop (HIL) setup.

Keywords:
Doubly Fed Induction Motor (DFIM); Modular Multi-level Converter (MMC); Fractional Order PID (FOPID) Controller; Total Harmonic Distortion (THD) Reduction; Wind Energy Conversion System (WECS).

Replaced conventional converters with MMC for improved efficiency and low harmonic distortion in WECS.

Applied MDHO and MAO-based FOPID controllers for MMC circulating current minimization.

Utilized LSPWM and 3D-SVPWM techniques for capacitor voltage balancing, enhancing DFIM performance.