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Efficient Computational Methodologies for Multi-Objective Optimization of Distributed Energy Resources (DER) Inverters


Efficient Computational Methodologies for Multi-Objective Optimization of Distributed Energy Resources (DER) Inverters

Vaddipalli, Rama Krishna Naidu ORCID: https://orcid.org/0000-0002-4575-5023 (2023) Efficient Computational Methodologies for Multi-Objective Optimization of Distributed Energy Resources (DER) Inverters. PhD thesis, Concordia University.

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The paralleling of power converters connected to the grid for power-sharing is a widely used technique. In this context, the design framework for a low-cost, lightweight, compact, and high-performance optimum configuration is an open research problem. This thesis proposes an innovative Multi-Objective Hierarchical Optimization Design Framework (MO-HO-DF) for an Alternating Current (AC) grid interface with N interleaved H-bridges, each with M parallel ``to-be-determined'' switches, connected through coupling inductances (Lf). A total of eight Figures of Merit (FOMs) were identified for the design framework optimization. A rigorous model of the power electronic system is presented. Next, a highly computationally efficient algorithm for the estimation of the required frequency modulation ratio (mf) to meet current harmonic performance requirements for any given configuration is proposed. Then, the concept and implementation of the algorithm are presented for the MO-HO-DF. The effectiveness of the design optimization framework is demonstrated by comparing it to a base case solution. Finally, the design calculations are validated via Piecewise Linear Electrical Circuit Simulation (PLECS) software with manufacturer-provided Three-Dimensional (3D) power semiconductor models that include thermal modelling.

In particular, when an H-bridge is interfaced with a single-phase grid, it requires controllers to regulate the voltages and currents in the system. In this context, the static optimization of controllers responsible for Direct Current (DC) bus voltage regulation and AC regulation, considering time-domain and frequency-domain behaviours, is an open research problem. Firstly, this thesis proposes a method to obtain FOMs with the use of inbuilt functions in MATLAB software. Then for the Type-II Proportional+Integral (PI) controller, a single-variable two-objective convex optimization is proposed. Next, for the Proportional+Multi-Resonant (PMR) controller, three-variable five-objective convex optimization is proposed. The design of the PMR controller is a multi-variable problem that can inherit the principles of a hierarchical framework and leverage the effect of a design variable on the final optimization result. Thus, the work on PMR controller design optimization is extended to a three-level hierarchical design framework and evaluates all six possible paths for optimization. Finally, enhanced macro-model-based MATLAB simulation results are provided to verify the performance of controller designs and generate statistical insights.

Divisions:Concordia University > Gina Cody School of Engineering and Computer Science > Electrical and Computer Engineering
Item Type:Thesis (PhD)
Authors:Vaddipalli, Rama Krishna Naidu
Institution:Concordia University
Degree Name:Ph. D.
Program:Electrical and Computer Engineering
Date:3 February 2023
Thesis Supervisor(s):Lopes, Luiz A. C.
Keywords:DER Inverter, Convex Optimization, PMR Controller, Resonant Controller, Power losses, compact power converters, Hierarchical, Type-II PI Controller, PLECS, Multi-Resonant Controller, computation in power electronics, miniaturization, FOMs, Figures of Merit, grid interface, Distributed Energy Resources, Total harmonic distortion, THD, double variable Fourier series,time-domain,frequency-domain, Stackelberg, multi-level,optimal-sequence.
ID Code:991902
Deposited On:05 Jun 2023 15:41
Last Modified:05 Jun 2023 15:41
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