Publications by Stefan Milovanovic

Performance Analysis of Energy Balancing Methods for Matrix Modular Multilevel Converters

Philippe Alexandre Bontemps, Drazen Dujic, Stefan Milovanovic

Modular multilevel converters achieve voltage scalability through the series connection of cells, each with its own capacitance. However, this converter structure using floating energy storage elements increases the control complexity significantly. The vo ...

2022

Virtual Capacitor Concept for Partitioning of Large Converter Systems for RT-HIL Simulations

Philippe Alexandre Bontemps, Drazen Dujic, Stefan Milovanovic

In this paper, the real-time simulation model of the modular multilevel matrix converter was split into three independent instances using the concept of virtual capacitance. In doing so, the number of state space matrices that define the system has been re ...

2022

Virtual Capacitor Concept for Computationally Efficient and Flexible Real-Time MMC Model

Drazen Dujic, Min Luo, Stefan Milovanovic

This paper demonstrates the splitting of the modular multilevel converter real-time simulation model into several independent parts through the use of the virtual capacitor concept. As a result, the number of state-space matrices the real-time solver needs ...

2021

Virtual Capacitor Concept for Effective Real-Time MMC Simulations

Drazen Dujic, Min Luo, Stefan Milovanovic

In this paper, the real-time simulation model of the modular multilevel converter was split into several independent parts through the use of the virtual capacitor concept. As a result, the number of state-space matrices the real-time solver needs to take ...

2021

Comprehensive Comparison of Modular Multilevel Converter Internal Energy Balancing Methods

Drazen Dujic, Stefan Milovanovic

Stacking of the floating structures, known as submodules or cells, provides the modular multilevel converter with theoretically unlimited voltage scalability. However, such a convenience comes at a price of increased control complexity, especially in the d ...

2021

Hardware-in-the-Loop Modeling of an Actively Fed MVDC Railway Systems of the Future

Drazen Dujic, Stefan Milovanovic

This paper presents an averaged real-time model of an arbitrary size MVDC railway system. In contrast to references already available in the literature, focusing mainly on specific parts of such a railway network (e.g. power converter installed in a locomo ...

2021

Distributed Real-Time Model of the M3C for HIL Systems Using Small-Scale Simulators

Philippe Alexandre Bontemps, Drazen Dujic, Stefan Milovanovic

Hardware-in-the-loop systems are an essential tool to verify controllers and deployed control algorithms in a risk-free environment. The inaccessibility of the converters used in applications such as pumped hydro storage power plants due to their high rati ...

2021

Flexible and Efficient MMC Digital Twin Realized With Small-Scale Real-Time Simulators

Drazen Dujic, Stefan Milovanovic, Milan Utvic, Ignacio Alejandro Polanco Lobos

2021

Comprehensive Spectral Analysis of PWM Waveforms With Compensated DC link Oscillations

Drazen Dujic, Stefan Milovanovic

In the available literature, including reference books on the topic, the spectral analysis of voltage waveforms obtained through the use of pulse-width modulation relies on the assumption of an ideally flat voltage across the DC link of a considered switch ...

2020

Flexible Medium-Voltage Perturbation Injection Converter for AC and DC System Identification

Marko Petkovic, Drazen Dujic, Stefan Milovanovic

2020

On Power Scalability of Modular Multilevel Converters: Increasing Current Ratings Through Branch Paralleling

Drazen Dujic, Stefan Milovanovic

The modular multilevel converter (MMC) presented in Figure 1 found its place within highvoltage and medium-voltage (MV) applications owing to the possibility of effortlessly meeting the imposed voltage requirements by stacking the so-called submodules (SMs ...

2020

MMC-based conversion for MVDC applications

Stefan Milovanovic

In recent years, DC grids have gained momentum due to the advantages they display over their AC counterparts. For instance, high voltage DC grids have been established as the most prominent solution in the underwater power transmission or interconnection o ...

EPFL2020

Modulation Considerations for Modular Multilevel Converter Operating with Parallel Branches and Phase-Shifted Carriers

Drazen Dujic, Stefan Milovanovic

The branch paralleling represents one of the available options with regards to the modular multilevel converter power extension. In such a case, the main technical challenge resides in the control domain, whereas a new set of possibilities from the voltage ...

IEEE2020

High-Power DC–DC Converter Utilising Scott transformer Connection

Drazen Dujic, Stefan Milovanovic

To obtain a resilient and flexible DC grid, reliable means for interfacing its parts operating under different voltage levels must be ensured. This paper proposes bidirectional, isolated, DC–DC converter designed to connect either high/medium voltage bipol ...

2019

Unidirectional High-Power DC-DC Converter Utilizing Scott Transformer Connection

Drazen Dujic, Stefan Milovanovic

2019

Comprehensive Analysis and Design of a Quasi Two-Level Converter Leg

Drazen Dujic, Stefan Milovanovic

Quasi two-level operation of voltage source converters, intended to operate either within high/medium voltage DC networks or low output frequency applications, has caught the attention of both academia and industry. Sequential insertion of the so-called su ...

2019

Flexible Medium Voltage DC Source Utilizing Series Connected Modular Multilevel Converters

Drazen Dujic, Stefan Milovanovic, Milan Utvic

This paper presents the converter configuration acting as a medium voltage DC source. In order to obtain desired voltage across the DC terminals, two series connected modular multilevel converters are used. The use of modular multilevel converters results ...

IEEE2019

On Facilitating the Modular Multilevel Converter Power Scalability Through Branch Paralleling

Drazen Dujic, Stefan Milovanovic

Modular multilevel converter current scalability challenge can be significantly alleviated by connecting its branches in parallel. In case a predefined submodule design is to be used with the aim of serving a certain span of applications, methods of achiev ...

IEEE2019

Comparison of two Modular Multilevel Converter Internal Energy Balancing Methods

Drazen Dujic, Stefan Milovanovic, Miodrag Basic

Although challenging, control of the modular multilevel converter internal variables has been addressed using several different approaches so far. With the aim of maintaining the submodules’ energies within a predefined band, the socalled circulating curre ...

IEEE2019

Flexible Medium Voltage DC Source Utilizing Series Connected Modular Multilevel Converters

Drazen Dujic, Stefan Milovanovic, Milan Utvic

This paper presents the converter configuration acting as a medium voltage DC source. In order to obtain desired voltage across the DC terminals, two series connected modular multilevel converters are used. The use of modular multilevel converters results ...

2019