Control of Grid Connected Active Converter: Design of Control Strategies for Grid Synchronization
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- Institutt for elkraftteknikk 
Application of power electronics in power distributed generation industry has been a fast evolving technology. This is due to the rapid shift from conventional non-renewable energy source to renewable energy source which led to the rapid rise of distributed generation. Efficient power generation from renewable energy source is highly dependant of the efficiency of the power electronics converter. Thus control of power electronics converter has been a vastly researched subject. In this thesis, a conventional cascaded control structure serves as a model for grid synchronization control design. Current and voltage control design and simulation will be the main research focus. Control system strategies are divided into approach with different type of controllers, hysteresis and proportional integral controller. It is further subdivided into approach with different control signal reference frame which consist of three phase stationary abc reference frame, two phase stationary αβ and synchronous dq reference frame. On top of this, a new voltage control structure approach which sees independent control of voltage magnitude and voltage frequency-phase angle is implemented too. In order to verify the theoretical study, simulation model is built and run for each methodologies presented. Control with PI controller in synchronous dq frame is found to be more reliable despite the pros and cons of each approach. Further detailed results and discussion of various applications together with proposal for future research are presented in the end of the thesis.