The modular multilevel converter (MMC) has been adopted as a good converter candidate in wind energy conversion systems (WECS) in recent years. Considering the control of the MMC based WECS, nearest level modulation (NLM) method is used to modulate and control the arm voltages of the MMC and capacitor voltage balancing is required to hold the capacitor voltage of each submodule (SM) of MMC constant. In this paper, experimental system is proposed to show the performances of the NLM and capacitor voltage balancing feedback control scheme in MMC based WECS. Experimental system is established using a wind DC generator, DC-DC boost converter, other experiment components and MMC topology including gate drivers and controller platforms. Accordingly, various case studies are performed to present the performance evaluation of the proposed experimental system. In this context, the capacitor voltage balancing scheme under NLM is validated using various case studies such as wind generator speed changes, different values of modulation index and different load condition using resistive and inductive load in the experimental setup of the MMC based WECS. In addition, the output voltage and current waveform with the capacitor voltages of upper and lower arm of the designed single-phase MMC circuit containing four SMs per arm are investigated and analyzed in terms of the total harmonic distortion and DC voltage utilization under different case studies for MMC based WECS.
Keywords: Wind energy conversion system, Modular multilevel converter, Nearest level modulation, Capacitor voltage balancing, Design for experiments.

Currently, Dr. A. Mete Vural is working as a full-time Associate Professor in Electrical and Electronics Engineering Department in Gaziantep University. He is leading Power Systems Research Group. He got his PhD degree in Electrical and Electronics Engineering from Çukurova University, Turkey in 2012. He worked as research assistant in Electrical and Electronics Engineering Department in Gaziantep University between 1999-2004 and in Automation and Process Control Engineering Department in Wuppertal University, Germany between 2004-2007. He also found in Strathclyde University, UK as a visiting scholar in 2000. His research interests are application of power electronics to power systems, multi-level converters, FACTS devices, power quality, microgrid, smartgrid, renewable energy, and energy storage.