Korreferent: Dr. Ganesh Kumar Venayagamoorthy

iAcknowledgement I would like to express my sincere gratitude to my advisor Prof. Dr.-Ing. habil. Istvan Erlich, whose encouragement, supervision and support from the initial to the concluding level enabled me to produce this thesis. His perpetual energy and enthusiasm in research had motivated me to do this Ph.D. I could not have imag-ined having a better advisor and mentor for my Ph.D study. I am privileged and proud to have worked under his esteemed supervision. I sincerely dedicate this thesis to him. I especially want to thank Prof. Dr.-Ing. habil.Gerhard Krost for his valuable guidance during my research. His great efforts to explain things clearly and sim-ply have helped a lot of young researchers, including me to successfully carry out my study at the university. I would also like to express my sincere thanks to my co-advisor Dr. Ganesh Kumar Venayagamoorthy for his valuable feedback, com-ments and suggestions to my dissertation. My heartiest thanks to Hannelore Treutler, for helping me with the administra-tive issues especially with my visa and Ralf Dominik, for providing all the soft-ware resources. I never started my day without the warm greetings from Rüdiger Reißig. Special thanks to him for making my stay at ‘Fachgebiet Elektrische Anlagen und Netze’, the most memorable part of my life. My deepest appreciation to my colleagues Koch, Jens, Shewarega, Befekad