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Thesis Defence: Numerically efficient modeling of modular multilevel converter with integrated battery energy storage for high voltage direct current transmission

April 14, 2023 at 9:00 am - 12:00 pm

Ogechuku Onyenenue, supervised by Dr. Liwei Wang, will defend their thesis titled “Numerically efficient modeling of modular multilevel converter with integrated battery energy storage for high voltage direct current transmission” in partial fulfillment of the requirements for the degree of Master of Applied Science in Electrical Engineering.

An abstract for Ogechuku’s thesis is included below.

Examinations are open to all members of the campus community as well as the general public.

Please email liwei.wang@ubc.ca to receive the zoom link for this defence.


The incorporation of large-scale energy storage into the existing power grid has resulted in a shift in the focus and interest of research and development efforts from traditional two- or three-level converters to modular multilevel converters. This is due to the flexibility of modular multilevel converters in allowing for the integration of battery energy storage systems within their submodule capacitors. Modular multilevel converters with integrated energy storage are currently being targeted for use in low- to medium-voltage grids, where the small battery cells can be efficiently distributed within the converter arms to increase the reliability of the power grid and maintain the necessary dc-link voltage. Therefore, it is essential to model and simulate these energy-storing converters in order to fully understand their operations, control, and performance in all scenarios prior to hardware implementation. However, modeling the complete, detailed circuit structure of modular multilevel converters using Electro-Magnetic Transient (EMT) simulation software, such as PSCAD/EMTDC, EMTP-RV, or MATLAB®/Simulink, can be a cumbersome and computationally expensive task, requiring significant CPU execution time due to the large number of submodules and circuit complexity.
In this thesis, a numerically efficient modeling method is proposed for modular multilevel converters with integrated energy storage. The method involves the use of a detailed equivalent model, which is capable of retaining the information and accuracy of the detailed model while eliminating the need of representing a large number of electrical nodes. This is achieved by using Thevenin equivalent circuits in the discrete time domain, which reduces the dimension of the equivalent conductance matrix in the EMT simulation. As a result, the computational burden of implementing the detailed converter model on a three-phase system is significantly reduced. When compared to the results of the detailed model, it was found that the equivalent model produces accurate simulation results and achieves a remarkable improvement of simulation efficient by 38 folds, compared to that of the DM for the 30-SM-per-arm modular multilevel converters with integrated energy storage.


April 14, 2023
9:00 am - 12:00 pm

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Event Type
Thesis Defence
Research and Innovation, Science, Technology and Engineering
Alumni, Community, Faculty, Staff, Families, Partners and Industry, Students, Postdoctoral Fellows and Research Associates