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Research Articles (Electrical Engineering)

Permanent URI for this collectionhttps://hdl.handle.net/10413/6858

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Browsing Research Articles (Electrical Engineering) by Subject "Electric power systems."

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    Quantitative Feedback Theory design of line current commutated HVDC control systems.
    (SAIEE Publications., 2013) Chetty, Leon.; Ijumba, Nelson Mutatina.
    Line Current Commutated (LCC) HVDC systems consists of uncertain plants. These uncertainties are result of changes/disturbances in the ac networks or in the LCC HVDC system itself. Further uncertainties can be introduced due to simplified system modelling techniques. Quantitative Feedback Theory is a frequency-domain technique that utilises the Nichols chart to achieve a robust design over a specified region of uncertainty. The Quantitative Feedback Theory design philosophy was applied to design the LCC HVDC control system parameters. The stable start-up and step responses of the LCC HVDC system, for varying ac system conditions, conclusively validate the Quantitative Feedback Theory design method of the LCC HVDC control system parameters.
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    System identification of classic HVDC systems.
    (SAIEE Publications., 2011) Chetty, Leon.; Ijumba, Nelson Mutatina.
    Determining models from observations and studying the models’ properties is essentially the functionality of science. Models attempt to link observations into some pattern. System identification is the art of building mathematical models of dynamic systems based on observed data from the systems. This paper presents a system identification methodology that can be utilized to derive the classic HVDC plant transfer functions. The model development and verification was performed using the PSCAD/EMTDC software. The calculated results illustrated excellent response matching with the system results. The derived HVDC plant transfer functions can be utilized to perform small signal stability studies of HVDC-HVAC interactions and its use can also be extended to facilitate the analytical design of HVDC control systems.