Close loop control for voltage control of mmc capacitors using carrier base pwm techniques

Abstract

quotBackground: newline Voltage Source Converter (VSC) technology has been becoming very popular in many of modern developing electric power systems areas, such as high-voltage direct current (HVDC) transmission systems (especially in offshore wind power transmission), STATCOM applications, medium-voltage motor drives, electric traction/propulsion systems, active harmonics filters, wind energy conversion system and grid-connected solar energy system or grid-connected energy storage systems. Conventional two or three-level VSC are the major part of the any applications of electric power systems today. For a high power, high efficiency, multilevel output, reliability and environmental compatibility, these conventional VSC are not adaptable. For high power application, two-level PWM inverter is not used due to switching losses. The solution to these problems has been evolved through the use of combinable, standardized, distributed, and simpler converter structures with lower voltage steps. newline newline newlineMultilevel converters have been come out as most appropriate competitors to the conventional VSCs in order to overcome the above mentioned limitations. Multilevel converters have numerous benefits for electric power conversion and this fact has been verified by a large no of research. Medium and high power DC-AC and AC-DC converters mainly able to generate a high voltage using a much lower rated power semiconductor switches. The stepped output nature of MLI not only puts less stress on the switching devices but it also produces less harmonics compared to two level inverters. No of MLI technology is present today like Neutral Point Clamp (NPC), Cascaded H-Bridge (CHB), Flying Capacitor (FC) and Modular Multilevel Inverter (MMC). At presently, modular multilevel converter (MMC) is at the heart of research and development studies in the area of power electronics. newline newlineAim: newlineThe aim of work presented in this thesis is to develop the different control algorithm for balancing the capacitor voltage of each sub module in a modular multilevel convert