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Eyvazizadeh Khosroshahi, Alireza

University of British Columbia

Growing demand for clean electricity has increased the importance and need of interface devices in power systems. High Voltage Direct Current (HVDC) systems seem to be a promising solution for future power systems. Hybrid topologies combine continuous AC side current, reactive power control, lower harmonics, smaller footprint, ability to supply weak AC grids, and black-start capability advantages of voltage source converters with low conduction loss advantage of line commutated converters. Hence, among different HVDC technologies, hybrid converters that combine thyristor based current source converters with multi-level modular converters (MMC) are predicted to prevail over other topologies. However, in practical systems the number of submodules in MMC-type converters is high. Therefore, the admittance matrix for these systems becomes very large and the detailed switching-based models are computationally inefficient to represent these systems in electromagnetic transient (EMT) type simulation environments. Average value modeling is a good solution for decreasing the complexity and increasing the computational efficiency of the detailed models. However, none of the previous research has focused on hybrid topologies with combined thyristors and insulated gate bipolar transistors (IGBTs) for converter valves. This thesis is filling the gap and develops detailed equivalent model (DEM), switching function based model (SFM), average chain-link model (ACM), and standard average value model (SAVM) for a thyristor-based hybrid three-level converter (TH3LC). During normal operation of TH3LC, the converter needs to block a few submodules in the commutation chain-link and therefore none of the previous models in the literature has implemented this feature for this converter. In this thesis, firstly different models are developed and formulated for TH3LC. Then, all the models are simulated and validated in MATLAB® Simulink environment. The results show that based on the study type and required accuracy, proper model should be chosen among DEM, SFM, ACM, and SAVM.

Text

2021-06-02

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/78508

Electrical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/