Multilevel Harmonic Elimination Methods For HVDC Using Pulse Width Modulation(PWM)

Direct current(DC)for the transmission is used rather than the conventional Alternating current(AC)in High voltage direct current(HVDC).The harmonic performance of the HVDC system highly depends on the modulation scheme.Literature review suggests that the lower pulse number PWM pattern numbers reduces the semiconductor losses consequently increasing the complexity of design of filter.Results were observed by using two level HEPWM technique.When the model h as been applied to voltage based convertor based HVDC good results are obtained.After a detailed literature review the already existing models were studied and different methods were proposed to decrease the complexity of the filtration system while ensuring consistent performance.The results obtained by the application of two level system is the main motivation to employ three level HEPWM in HVDC application.The main target is to decrease the losses resultantly having better performance with almost same complexity of the system.For this three different models are designed and their performance is compared.The results were observed and then future prospects are also discussed.MATLAB calculations will be verified by using a steady state model for new topology in PSCAD simulation.A detailed comparison of all the models have been also presented in this thesis.