Analytical Efficiency Evaluation of Modular Multilevel Converter (MMC) for High Voltage Direct Current System (HVDC)

Table of Contents

Chapter 1: Introduction

1.1 Problem Statement

1.2 Aim and Objective

1.3 Scope of Work

1.4 Organisation of Thesis

Chapter 2: Literature Review

2.1 Introduction

2.2 Literature Review

Chapter 3: Modular Multilevel Converter

3.1 Introduction

3.2 Modular Multilevel Converter (MMC).

3.2.1 Features of Modular Multilevel Converter (MMC).

3.2.2 Advantages of Modular Multilevel Converter (MMC).

3.2.3 Working of Modular Multilevel Converter (MMC).

3.3 Sub Module Topologies

3.3.1 Half Bridge Sub Module.

3.3.2 Full Bridge Sub Module.

3.3.3 Clamp Double Sub Module.

Chapter 4: Average and RMS Values Calculation

4.1 Introduction

4.2 Circuit Ananlysis

4.3 Conversion Losses.

4.3.1 Conduction Losses.

4.3.2 Switching Losses.

4.4 Half Bridge Sub Module Calculations

4.4.1 Average Value of the Current.

4.4.2 RMS Value of the Current.

4.5 Full Bridge Sub Module Calculations

4.5.1 Average Value of the Current.

4.5.2 RMS Value of the Current.

4.6 Clamp Double Sub Module Calculations.

4.6.1 Average Value of the Current.

4.6.2 RMS Value of the Current.

Chapter 5: Power Losses Estimation

5.1 Introduction

5.2 Half Bridge Sub Module

5.2.1 Conduction Losses.

5.2.2 Switching Losses.

5.3 Full Bridg Sub Module.

5.3.1 Conduction Losses.

5.3.2 Switching Losses.

5.4 Clamp Double Sub Module.

5.4.1 Conduction Losses.

5.4.2 Switching Losses.

Chapter 6: Solution based on MATLAB Simulation: Case Study.

6.1 Introduction

6.2 Half Bridge Sub Module

6.3 Full Bridge Sub Module.

6.4 Clamp Double Sub Module.

6.5 Summary

Chapter 7: Conclusion.

7.1 Conclusion of Research Work.

7.2 Future Directions.

Research Objectives and Focus

The primary aim of this research is to develop an analytical method for calculating conversion losses and efficiency of various sub-module topologies used in Modular Multilevel Converter (MMC) based HVDC systems, providing engineers with a reliable tool for system design and optimization.

• Analysis of MMC sub-module topologies including half bridge, full bridge, and clamp double configurations.
• Derivation of mathematical models for conduction and switching losses based on average and RMS current values.
• Development of a MATLAB-based simulation program to evaluate performance metrics under varying parameters.
• Comparative study of efficiency and power loss characteristics for different sub-module designs.

Excerpt from the Book

Summary of Chapters

Chapter 1: Introduction: Provides an overview of HVDC systems, identifies the design challenges in MMC technology, and outlines the thesis objectives and structure.

Chapter 2: Literature Review: Surveys existing research on MMC loss estimation techniques from 2003 onwards, establishing the need for the proposed analytical method.

Chapter 3: Modular Multilevel Converter: Details the construction, working principles, and specific features of MMC, comparing various sub-module topologies like half-bridge and full-bridge.

Chapter 4: Average and RMS Values Calculation: Derives the mathematical relationships for average and RMS currents flowing through switching devices under different operating conditions.

Chapter 5: Power Losses Estimation: Calculates conversion losses for each sub-module topology using the derived current equations from the previous chapter.

Chapter 6: Solution based on MATLAB Simulation: Case Study: Presents simulation results, including efficiency curves and loss analysis, to validate the derived analytical models.

Chapter 7: Conclusion: Summarizes the key findings of the research regarding sub-module efficiency and provides recommendations for future investigative work.

Keywords

Modular Multilevel Converter, MMC, HVDC, Power Electronics, Conduction Losses, Switching Losses, Half Bridge, Full Bridge, Clamp Double Sub Module, MATLAB Simulation, Efficiency, IGBT, Current Analysis, RMS Value, Transmission System.

Frequently Asked Questions

What is the main focus of this research?

The research focuses on accurately calculating and comparing conversion losses and efficiency for different sub-module topologies within MMC-based HVDC transmission systems.

What are the primary sub-module topologies discussed?

The thesis examines the half bridge, full bridge, and clamp double sub-module topologies.

What is the primary objective of this work?

The goal is to provide design engineers with a robust analytical method and a MATLAB-based tool to estimate semiconductor power losses during the design phase of MMC systems.

What scientific methodology is employed?

The study utilizes an analytical approach based on the calculation of average and root mean square (RMS) values of currents flowing through semiconductor devices to derive loss and efficiency formulas.

What is covered in the main body of the thesis?

The main body covers the theoretical background of MMC, the mathematical derivation of current-based loss models, and the numerical verification of these models through MATLAB simulations.

Which keywords best characterize this work?

Key terms include Modular Multilevel Converter (MMC), HVDC, semiconductor power losses, efficiency estimation, and sub-module topologies.

Why is MMC preferred over traditional VSC topologies in this context?

MMC is noted for its low switching frequency, low converter losses, flexible control, and easier scalability, making it ideal for modern HVDC applications.

What effect does the junction temperature have on losses?

The research acknowledges that junction temperature significantly impacts semiconductor device performance and incorporates it into loss considerations using temperature coefficients.

How does the clamp double sub-module compare to the full bridge?

The analysis indicates that the clamp double sub-module has higher total power losses compared to the full bridge due to the inclusion of additional transistors and diodes.