DCE &S de... · Distributed renewable energy sources are either DC inherently, e.g. photo voltaics,...

D C E & S

DC Systems, Energy

Conversion & Storage

Title: Distributed Real-Time Markets and Demand Response in DC Microgrids

Type of project: MSc thesis

Scope: Investigation of new possibilities for distributed markets in DC distribution grids. Close

coupling of real-time markets with the physical needs of the system.

Problem definition: Nowadays most electric loads use DC. Even AC motors are more and more driven

by motor controllers using AC/DC followed by DC/AC conversion which allows variable speed control.

Distributed renewable energy sources are either DC inherently, e.g. photovoltaics, or use a DC link to

decouple rotations speeds from the AC grid such as wind power. Batteries are DC in general and their

application is evolving in electric vehicles and other devices. Therefore it is reasonable look into using

DC to connect all these DC sources and loads. Our research focusses on finding the “optimal” low

voltage DC microgrid system, implementing all smartgrid features needed in future. This can then be

put into standards for an universal DC distribution system. We are building a real DC lab to verify our

findings. As the usual voltages are 350 V – 400 V we can build it 1:1. The lab grid will consist of a

number of DC/DC converters that will emulate typical sources and loads.

Methodology: This project will be mainly done with simulations. Depending on progress also an

implementation in our lab setup is possible.

Research Objectives:

Physical market clearing

How much reserve power needed?

Congestion management

Optimal power flow in DC grids

Congestion rent

Voltage dependent pricing

Real time market participation

Price forecast

Storage management

Voltage dependent demand response

Collaboration with Industry: No. Two master students will work on this topic and a division of the

tasks will be discussed together. Also collaboration with other master and PhD students in the DC

microgrid team is essential for success.

Contact details:

PhD student: Laurens Mackay, [email protected]

Supervisor: Laura Ramirez Elizondo, [email protected]

Pavol Bauer, [email protected]

1

D C E & S

DC Systems, Energy


Title: Power Electronics in DC Microgrids


Scope: Designing DC/DC converters for use in DC microgrids.











Methodology: This project will include simulations, design of hardware and implementation of

control and communication in our lab setup.


Bidirectional DC/DC converters for DC microgrids.

Possibly hardware implementation of solid state circuit breakers.

The concrete objectives have to be specified in summer depending on progress of current

master students.

Collaboration with Industry: No

Collaboration with other master and PhD students in the DC microgrid team is essential for success.

Contact details:




2

D C E & S

DC Systems, Energy


Title: DC Microgrid Projects à la Carte

Type of project: Extra Project / SIP 2 / MSc Thesis

Scope: We have plenty of things that can be done in our lab setup. If you would be interested or have

some specific ideas, please tell us.











Methodology: These projects can include simulations, design of hardware and implementation of

control and communication in our lab setup.

Possible Objectives:

Hardware

Communication between Linux computer on module and microcontrollers using i2c bus

TCP/IP communication to Matlab Simulink on a host computer.

Programming, Simulink, Code Composer Studio, TCP/IP network, flashing microcontrollers.

Optional would be the addition of WiFi, IPLo6WPAN, ZigBee networks.

We are open for other ideas.

Collaboration with Industry: Possible. Collaboration with other master and PhD students in the DC

microgrid team is essential for success.

Contact details:




3

Title: Control and modelling of DC Microgrid

Type of project: MSc Thesis

Scope:

1. Build models of converters for DC microgrid

2. Build models of different DC microgrid architectures for control study

Problem definition:

The systematic models of converters for studying DC microgrid is one of the main challenges.

Different kinds of models are needed for different DC microgrid behaviour studies. Control,

protection, communication and market models need different approaches of modelling of DC

microgrid.

Methodology:

Matlab Simulation is expected.


• Investigating DC microgrid architectures

• Identify and model different types converters for DC microgrid architectures

• Identify methods of modelling for control, protection and market models

• Create new control method of selected architecture model


Contact details:

• PhD student: T.G.Hailu, [email protected]

• Supervisor: Laura Ramirez, [email protected],

J.A.Ferreira,[email protected]

4

Title: Power Line Communication for DC Microgrid


Scope:

The use of power line communication(PLC) for control of the system dynamics in a DC microgrid is

not well investigated. This project aims to have some understanding on the possibilities of using

power line communication for system dynamics control of DC microgrids and nanogrids

Problem definition:

The use of power line communication for internet, home automation and smart metering is a

common practice. Moreover, steady state control communication for setting states of a source or a

load is implemented using power line communications. This project investigates the possibility of

using power line communication in fast control dynamics of a system either for system stability or

system protection.

Methodology:

Matlab Simulation and practical testing on a testbed of DC microgrid is expected.


• Identify different types of PLC methods, PLC modems

• Investigating and designing of network impedance, cable types

• Analysis signal fidelity in the network and propose a method of improving network

impedance matching

• Simulate, Build and test PLC system identified on test set up for system dynamics control


Contact details:

• PhD student: T.G.Hailu, [email protected]

• Supervisor: Laura Ramirez, [email protected], J.A.

Ferreira,[email protected]

5

Title: A Standard Approach for DC Microgrid

Type of Project: MSc Thesis

Scope:

1. To design the Power Router (pRouter) in DC microgrid 2. To design the communication protocol, both at Local Area Network (LAN) level and

Network/Transmission Layer level. Both are to be implemented with Power Line Communication (PLC).

Problem Definition:

Studies on microgrid has simply gone too wild and it is time for a standardized approach to design commercial products. The weak nature of microgrid is studied and set as fundamental difference to the studies of bulk grid, like what is often seen in some publications by taking the same assumption as in HVDC studies, and is often misleading. A 300 W or inter‐leaved 1 kW fly‐back converter working at DCM/BCD mode is defined as the generic power electronic converter (GPEC). A 18 kW power router is defined, which provides safety disconnection with built‐in electronic arc elimination circuit, as well as conventional anti‐lightning protection and leakage current protection. Apart from electric functions, it also provides information functions not only for monitoring but also for electric pricing‐based power flow control. Methodology:

In a naturally weak grid of DC microgrid, power converters are only to handle the transient generation/consumption change. Energy exchange over a longer time span (usually in the scale of multiple minutes) is to be negotiated through PLC communication with other sub‐networks, which are electrically connected to the DC microgrid, because no electrical measurement outside its own sub‐network is practical in this application. Communication protocol, therefore is the only means for power flow control in the DC network, and monitoring the power converters is becoming a secondary task of PLC. The methodological approach is preliminary defined as a refinery of Multi‐Agent Approach.


A Hybrid protocol is to be drafted. It is a combination of Master‐Slave and CSMA/CD principle. Pricing mechanism to be formed for power flow of the DC microgrid, which is the prime task of pRouter

A routing algorithm shall be implemented to form a path to transfer power from remotely connected sub‐network. This can be roughly understood as a simplified IP protocol equivalent.

Contact details: Post Doctorate Researcher: Dr. GU Junyin, LB 03.640, [email protected] Supervisor: Prof. J.A. Ferreira , LB 03.500, j.a.ferreira@tudelft,nl

6

Title: Designing High Power Density Generic Power Converter for DC Microgrid

Type of Project: MSc Thesis

Scope:

1. To design the Generic Power Electronics Converter (GPEC) 2. To optimize the transformer design (planar transformer) and to improve the soft switching

performance (above 500 kHz with Cool MOS or GaN)

Problem Definition:

Studies on microgrid has simply gone too wild and it is time for a standardized approach to design commercial products. The weak nature of microgrid is studied and set as fundamental difference to the studies of bulk grid, like what is often seen in some publications by taking the same assumption as in HVDC studies, and is often misleading. A 300 W or inter‐leaved 1 kW fly‐back converter working at DCM/BCD mode is defined as the generic power electronic converter (GPEC), due to following reasons: the current control can be achieved at an open loop approach, easing the most difficult part of controller design; the output impedance is inherently high and can be set to an arbitrary value in the same open loop approach, making it instantly ready for power extension (paralleling at output) and also for different applications (like battery charger, voltage source, LED driver, PV module simulator, and but not limited to arc welder). High power density of 50 W/cm3 and high conversion efficiency of 97% are achieved with soft‐switching of 300‐500 kHz. Methodology:

BCM Flyback with DSP assisted soft switching of 300‐500 kHz is to be employed as the main hardware topology. Firmware is to be designed in modular approach, with SoC/MPPT/Droop Control as standard functions. Communication protocol is designed in a separated Master’s Thesis.


Soft switching above 500 kHz with Cool MOS and GaN Power density of 50 W/in

3 with natural cooling Current sensor‐less control/Open loop approach

Contact details: Post Doctorate Researcher: Dr. GU Junyin, LB 03.640, [email protected] Supervisor: J Popovic, [email protected]

7

D C E & S

DC Systems, Energy

Conversion & StorageMSc thesis: Energy management system for a solar powered

industrial area with large EV penetration

Scope & Research Objectives:

Energy management system design for solar powered industrial are with large number of EV

Optimisation of power flows based on grid conditions, solar forecast, and electricity prices.

Problem definition:

The EV-PV project aims at developing an electric vehicle charging infrastructure at workplace using PV

panels. The focus is to reduce the energy demand on the grid due to electric vehicles by locally producing

the charging power in a ‘green’ manner through solar panels. The long time for which the EVs are parked

at the office paves way for implementation of Vehicle-to-grid (V2G) technology where the EV acts as a

controllable power generator. In this MSc thesis, an energy management system will be designed that

performs the optimisation of power flows in a solar powered industrial area with large number of EV.

Methodology:

1. Analysis of power flows in industrial area with high penetration of EV-PV

2. Defining load profiles for EV, PV, industrial area, V2X demand and (optional) local storage

3. Simulation of scenarios in MATLAB/GAMS based on solar/grid/price forecast to maximise EV

charging from PV and supply loads with minimum grid dependency/cost.

4. Enhance the optimisation considering grid conditions like line loading, losses, voltage issues at

nodes and transformer loading

Collaboration with Industry:

ABB, EV charging infrastructure, Rijswijk

Contact details:

PhD student: Gautham Ram <[email protected]>

Supervisor: Laura Ramirez <[email protected]>

Pavol Bauer < [email protected]>

8

mailto:[email protected]


D C E & S

DC Systems, Energy


MSc thesis: Increasing grid integration limits of EV and PV

Scope:

1. Network modelling, power system analysis

2. Smart charging of electric cars

Problem definition:

Large scale integration of PV and EV has adverse effects on

the distribution network. The grid is not currently designed

to handle the large power being fed by solar panels and the

high power demanded by EV for charging. Problems arise

in the distribution network in the form of:

1. Under-voltage and over-voltage at feeder ends

2. Increased losses and possible overloading of cables

and lines at feeder head

3. Overloading of distribution transformers.

However if the EV are locally charged directly from PV, then the grid power injection due to PV and

power demand from grid due to EV are mutually solved. Workplace like office buildings are ideal places

to setup such EV-PV chargers where employee cars can be charged in a sustainable way from the PV

panels installed on top of building roof or parking areas.

Methodology:

1. Model the Dutch distribution network in a software package for load flow analysis

2. Perform load analysis to determine the grid integration limits for connecting PV arrays

3. Determine the grid violations that occur when the PV penetration levels increase

4. Similarly repeat the load flow analysis for estimating the highest possible grid integration levels for

EV. What is the limiting factor for high penetration of EV?

5. Consider a scenario where EV are charged directly from PV using an EV-PV charger. Determine

the combined integration limits for EV and PV using such EV-PV chargers. Determine if the grid

integration limits are increased when EV charging is combined with PV generation?

6. Can smart charging techniques be implemented to further increase the integration of EV-PV?


Increase the penetration levels of EV and PV in the electricity grid

Smart charging of EV in a sustainable method by using PV arrays at workplace



Alliander

Contact details:


Supervisor: Laura Ramirez <[email protected]>

Pavol Bauer < [email protected]>

9



D C E & S

DC Systems, Energy


MSc thesis: Optimal topology for a multi-port EV-PV charger

Scope:

1. Comparison of power electronic converter design

2. Analytical estimation and simulation of converter

Problem definition:

The EV-PV project aims at developing an electric vehicle charging infrastructure at workplace using PV

panels. The focus is to reduce the energy demand on the grid due to electric vehicles by locally producing

the charging power in a ‘green’ manner through solar panels. The long time for which the EVs are parked

at the office paves way for implementation of Vehicle-to-grid (V2G) technology where the EV acts as a

controllable power generator for the grid. In this MSc thesis, the most optimal power converter topology

for a three port converter for integrating EV, PV and grid has to be determined.

Methodology:

1. Literature study of (three-port) power converters for EV charging and PV inverter application

2. Analytical design of the chosen topologies of power converter.

3. Simulation in MATLAB/PLECS

4. Comparison of converters on basis of efficiency, component count, harmonics, ease of control


Development of a high efficiency three-port converter for EV charging from PV

Comparison of converter based on indices to determine most suitable topology.


PRE, Power research electronics B.V, Breda


Contact details:


Supervisor: Pavol Bauer < [email protected]>

10



D C E & S

DC Systems, Energy


MSc thesis: High efficiency isolated power converter for EV charging

Scope:

1. Power electronic converter design

2. Soft switching techniques for high efficiency power conversion

3. Experimental setup of converter and testing

Problem definition:

Bidirectional EV chargers will enable both charging of EV and vehicle-to-grid V2X operation. DC

charging EV standards currently plan to implement 10kW of bidirectional charging/V2X operation. The

goal of the project is to develop such a high efficiency EV charger that charges EV battery corresponding

to a wide voltage range.

Methodology:

1. Literature study of isolated converters for EV charging application

2. Analytical design of the chosen topology of DC/AC converter

3. Simulation of converter in MATLAB/PLECS

4. Experimental setup of converter and verification of operation


Development of a high efficiency AC/DC converter for EV charging

Experimental setup to verify the design


PRE, Power research electronics B.V, Breda


Contact details:


Todor Todorcevic <[email protected]>

Supervisor: Pavol Bauer < [email protected]>

11




D C E & S

DC Systems, Energy


Title: Linear Programming (LP) Model of Heat Network Flows


Scope:

Combined heat and power (CHP) is a technology that decreases total fuel consumption and related

greenhouse gas emissions by producing both electricity and useful thermal energy from a single

energy source. To optimally exploit the flexibility of CHP units, their connection to the electricity and

heat networks must be adequately modeled. Although there is plenty of literature about modelling

CHP units including electricity network, there is few including heat network.

Problem Definition:

Heat network flows must be modelled in a computationally efficient way, so it can be include in more

computationally demanding scheduling problems, such as unit commitment (UC) (which is a mixed-

integer linear problem). So, the network flows should be preferably modelled under the linear

programming (LP) approach, thus avoiding high computational complications.

Methodology:

The project is about developing mathematical models and implement them as LP models, so

simulations can be carried out.


Perform a literature review about different models for optimal heating flows

Create an LP model of heat network flows.

Clearly assess the advantages and disadvantages of modelling heat network flows as an LP

Couple heat network flows with an UC problem.

Assess the economical impact of including heat network flows within UC problems.


Contact details:

Postdoc researcher: Dr.ir. Germán Morales-España , [email protected]

Supervisor: Dr.ir. Laura Ramirez, Dr.ir Pavol Bauer, [email protected]

12

D C E & S

DC Systems, Energy


Title: Tight Modeling of Combined Heat and Power Units in Unit Commitment


Scope and Problem Definition:

Combined heat and power (CHP) is a technology that decreases total fuel consumption and related

greenhouse gas emissions by producing both electricity and useful thermal energy from a single

energy source. To optimally exploit the flexibility of CHP units, their CHP units need to be optimally

scheduled in advance to adequately cover an expected electricity and thermal demands. This optimal

schedule is achieved by solving the so-called unit commitment (UC) problem. However, taking into

account all CHP technical operating constraints, such as minimum up/down times, start-up and shut-

down procedures, make the computational problem highly demanding.

Mixed-Integer Linear Programming (MIP) has become a very popular approach to solving UC

problems due to significant improvements in off-the-shelf MIP solvers. Despite the significant

improvements in MIP solving, the time required to solve UC problems continues to be a critical

limitation that restricts their size and scope. Nevertheless, improving an MIP formulation can

dramatically reduce its computational burden and so allow the implementation of more advanced

and computationally demanding problems, like optimal scheduling of CHP units.

Methodology:

The project is about developing mathematical models and implement them as MIP models, so

simulations can be carried out.


Create a tight and compact MIP model of CHP units.

Assess the economical impact of an adequate modeling of CHP units in UC problems.


Contact details:



13

D C E & S

DC Systems, Energy


Title: Unit Commitment with "green curtailment" of wind and solar power

generation Include


Scope and Problem Definition

Renewable energy targets and incentive mechanisms have been adopted around the world and have

been successful in promoting wind and solar development. Examples include European countries for

meeting European Union (EU) 2020 targets. Most systems operators in Europe use as much

renewable energy (wind and solar) as possible during the daily operation, hence renewable energy is

never curtailed unless the power system is at risk. Although numerous studies have shown that not

allowing curtailment reduces system flexibility and increases system operating costs, the "zero

curtailment" policy remains as a dominant policy in order to reduce CO2 emissions and thus making

power systems more green every time.

If curtailment is not allowed when dealing with high penetration levels of renewable energy, then

conventional power plants are started up and shut down more often, which in many cases lead to

higher CO2 emissions. In other words, these "green policies" can be counterproductive, in fact wind

po er’s effecti e incremental emissions can be higher than the most polluting power plant in the

system. To avoid this, curtailment must be permitted in a smart and optimal way so guaranteeing

that any curtailment would actually reduce CO2 emissions.

Therefore, optimal planning of power systems must now include optimal "green curtailment" of

renewable resources. This can be achieved by solving the so-called unit commitment (UC) problem.

The UC consists of optimal resource scheduling in electric power systems to minimize the total

system operational costs, while operating the system and units within secure technical limits.

Methodology: Perform simulations and modify already available UC formulations


Create green curtailment policies that minimize CO2 emissions through solving an UC

problem.

Build a case study where green curtailment can be optimally scheduled within a centralized-

UC framework.

Assess the economical and CO2-emmisions impact of different curtailment policies on

different penetration levels of renewable energy.

Draw policy recommendations to introduce wind curtailment in electricity markets


Contact details:



14

D C E & S

DC Systems, Energy


Title: Smart Grid Cell Optimization on EV charging (fast/normal)

Type of project: Internship/MSc thesis

(Solar based EV charging in Toronto. Source: wikipedia)

Scope: There has been an unprecedented proliferation of Electric Vehicles (EV) in recent past. While

gree - i ded users s it h to EVs to ause lesser e ologi al i pa t due to ur a o ility, the hargi g of EV still can pose major problems. First of all, it only makes sense to use the sustainability argument in

the E-mobility space if the EVs are largely charged from a non-fossil based grid or Renewable Energy

Sources (RE) or a combination thereof.

Problem definition: While local RE generation has led to the rapidly e ol i g real of “ art Grids , u h is yet to be answered in the EV charging space to fit in the smart grid landscape. This project aims to

scientifically answer some of the most pertinent questions in a Dutch scenario for interconnected Smart

Grid cells.

Methodology: The student is expected to present his/her findings in the form of a scientific report and

presentation(s) that conform with the norms of the DCE&S group, and TU Delft in general.


Impact on the power and energy balance of the smart grid cell due to various EV charging

strategies

Exploiting local storage for EV charging and smart grid cell optimization via:

o Demand side management

o Energy supply management

Optimal scheduling for energy charging (real-time power allocation)

Real time optimization of EV fast charging with control design

Optimizing interconnected smart grid cell blocks given EV charging scenarios

Collaboration with Industry: Yes, DNVGL, ALFEN, ALLIANDER, HAN

Contact details:

PhD student: Nishant Narayan, [email protected]

Supervisors:

Laura Ramirez, [email protected]

Pau Bauer, [email protected]

15

D C E & S

DC Systems, Energy


Title: Modelling PV Battery Architectures for Integrated Module

Type of project: Extra Project/ SIP 2

Fig 1. Architectures proposed

Scope: Due to the stochastically-changing nature of the solar radiation, it is necessary to incorporate

energy storage systems in order to supply energy when the sun is not available.

It is also known that the cost of the solar systems has to be reduced to compete with other

renewable energy sources and specially with fossil fuels.

The installation cost of PV battery systems nowadays is one of the main initial cost. This cost could be

reduced by incorporating the battery, DC/DC converter, charge controller, DC/AC microinverter and

intelligent power management as a compact unit at the back side of the PV module.

Problem definition: In order to integrate the components mentioned above, an electric

configuration and optimal energy storage has to be found.

An intelligent power management will charge the battery of the solar panel in moments when there

is high solar illumination and no power consumption in the house and directly feed the loads when

there is power consumption.

Methodology: Simulation related to the Intelligent Power Management proposed has to be

performed.


Size the PV Storage systems for the architectures proposed

Simulate the intelligent power management for the architectures proposed

Compare the obtained results for the architectures proposed


Contact details:

PhD student: Víctor Vega, [email protected]

Supervisor: Laura Ramírez, [email protected], Paul Bauer, [email protected]

16

D C E & S

DC Systems, Energy


Title: Environmental Footprint of Power Electronic Converters


Scope:

Power Electronic Converters (PEC) are essential for connecting Renewable Energy Sources (RES) to

the power grid. However, during the design phase of these converters, Life Cycle Assessment (LCA)

parameters are often neglected. Because of this, it is almost impossible to get a clear insight into

contribution of PEC to the sustainability aspect of RES.

Methodology:

The goal of this project is to develop a tool to determine LCA parameters of any given PEC. In order

to do so, the student is required to design an approach and implementation of LCA for PEC. In

addition to that, the student should also gather data in order to build a database with LCA

parameters of several PECs.


Develop an approach/algorithm for LCA of converters

Write an application/script that calculates LCA parameters of converters based on user input

Create an extendable database with LCA parameters of several converters


Contact details:

PhD student: Aniel Shri <[email protected]>

Supervisor: Jelena Popovic <[email protected]>

17

D C E & S

DC Systems, Energy


Title: Battery models for Low-Voltage AC/DC Grids


Scope:

Grid regulations limit the amount of energy that Renewable Energy Sources (RES) are allowed to feed

back to the grid. One way to overcome this limitation is to temporarily store the energy in batteries.

Different battery charge- and discharge management systems result different behaviour of the

system which it is connected to. The goal of this project is to determine the most efficient battery

management system for different DC-grid architectures.

Methodology:

After identifying different battery models and management systems, the student will translate these

models to MATLAB/Python based models. After which the models will be used to determine their

effectiveness in both AC and DC grids.


Translate battery models and management systems found in the literature to

MATLAB/Python based models

Evaluate the advantages and disadvantages of the different models for storage of renewable

energy


Contact details:

PhD student: Aniel Shri <[email protected]>

Supervisor: Jelena Popovic <[email protected]>

18

Title: Very high frequency power conversion (>10MHz) for LED drivers with GaN devices


Scope: The goal of this challenging project is to investigate suitable circuit topologies and operating modes for GaN‐HEMT based very high frequency power conversion. Topologies are to be evaluated with respect to power loss/efficiency, loss distribution between active and passive devices, complexity, system integration, gate driving etc. This includes topologies inherited from switched mode RF power amplifiers and more conventional power electronics resonant topologies.

Problem definition:

Due to their fast switching and low losses GaN power semiconductor technology offers great potential in power electronics in terms of efficiency increase, miniaturisation and new applications. LED lighting has a potential to be a very suitable application for performance increase due to GaN and push necessary market adoption of GaN.

Methodology:

The project will include review and assessment of suitable topologies, design of the most promising candidate through model development and simulations and practical implementation on a hardware demonstrator.


‐ Review of topologies suitable for very high frequency conversion

‐ Analysis of the most suitable topologies

‐ Demonstrator design in the chosen topology including issues such as gate drivers, layout etc.

Collaboration with Industry: Yes, Philips Lighting.

Contact details: PhD student: Aniel Shri, [email protected] Supervisor: Jelena Popovic, [email protected]

19

Title: Developing PWM for power electronics practicals

Type of project: Extra Project

Fig. 1: TMS320F28027, C2000 LaunchXL mounted on an experimental interface board. http://www.ti.com/ww/en/launchpad/launchpads‐c2000.html

Scope:

For the practical of new MSc course “Advanced Power Electronics” a pulse generator is needed. This document roughly describes the specification of the pulse generator, which is based on a 32 bits C2000 microcontroller from Texas Instruments (see Fig. 1). It gives additional information to e.g. a MSc student who is interested in an extra project of 1‐2 months within our ESE‐department.

Objectives:

Develop software that generates a single PWM signal for the control of a Boost Converteri with the following specifications.

Inputs: Frequency (f) Set points from external potentiometers on the interface board, which are coupled to the ADC inputs. Duty (D)

1x optional ADC input for future control purposes Outputs: PWM f = 10kHz … 200kHz, D = 5 … 95%Contact details:

Bart Roodenburg, [email protected] Jelena Popovic [email protected]

Time line We are looking for a student who can start as soon as possible but no later than May 1st, 2015. i : Power electronics (Chapter 7), Mohan, Undeland, Robbins, 3rd Edition 2003

20

Title: Optimal phase shift in BCM PFC circuits


Scope:

Reduction of EMI filtering effort in PFC circuits that run in BCM mode. This mode is preferable for hf operation (e.g. with GaN switches). Comparison with CCM mode to be made.

Problem definition:

For high power power factor correction circuits (PFC) the EMI filter becomes very large. One of the proposed remedies for that is to interleave two PFCs. Then only the resulting current has to be filtered. In literature 180° phase shift is generally assumed. However: it might be questionable whether this is the right choice taken the required EMI filter into account.

A complicating factor is that a practical BCM PFC has also an idle time during which the drains voltage rings to a minimum. Has that a large impact?

Methodology:

Interference model for the interleaved stages, simulations & mathematical proof. Both for CCM and BCM

Idem for idle time between switching cycles (with idle time as a variable)

If time permits: build a prototype for verification


optimal interleaving strategy for multiphase PFC circuits, and whether they are different for CCM and BCM.

Assess the influence of idle time in BCM/ZVS mode

assess what really defines the size of the EMI filters in PFC circuits.

Contact details: Supervisor: F. Pansier, [email protected] Supervisor: J. Popovic, [email protected]

21

Title: High frequency flyback transformers

Type of project: MSc project

Scope:

Investigate the optimal technology for realisation of flyback transformers, that can operate it >> 500kHz, with mains isolation, for power level up to 120W,

Problem definition:

For power supplies the flyback topology are mainstream, due to its simplicity and low cost. However: the transformers exhibit also quite some leakage inductance. For high frequency this lead to problems with manufacturability and/or performance. The winding technology that is in wide spread use is for sure not suitable anymore. Some technologies for improving the coupling between primary and secondary are known, (foil windings, multilayer planar) but they exhibit quite some parasitic capacitance, reducing efficiency, and/or are detrimental for EMI. Not finding a suitable transformer technology might inhibit the use of WBG semiconductors (esp. GaN) . Goal is to gain insight into the best way to be able to increase the switching frequency. Technology for hf operation of transformers for resonant topologies like LLC, with integrated magnetics, can be investigated as well.

Methodology:

Survey of potential techniques for hf transformers with mains insulation, including parasitics Check consequences in flyback topology, at first using simulation. Build two different version of transformers to verify the behaviour in a real circuit Research Objectives:

Overview of potential technology for mains isolated flyback transformers Check limits of each technology, in conjunction with the optimum operation of a flyback

converter using that type of transformer Gain knowledge on the potential for GaN (=hf operation) in this type of converters (or in

other words: can the benefits of WBG semiconductors also lead to a breakthrough in low power mains isolated power supplies

Contact details: Supervisor: F. Pansier, [email protected] Supervisor: J. Popovic, [email protected]

22

Power loss analysis and characterization for surface mounted rectifier in high frequency voltage multiplier circuits


Scope:

Analyse the power loss for surface mounted rectifier in high frequency voltage multiplier circuits. Develop the research methodology to characterize the surface mounted rectifier power loss considering the rectifier conduction & switching characteristics, rectifier junction capacitances in high frequency, and high temperature environment.

Problem definition:

The rectifier is key components for voltage multiplier circuits used for high frequency high voltage power conversion circuit. The accurate power loss analysis of rectifier in high frequency, and high temperature environment is critical for voltage multiplier circuit performance such as power efficiency, temperature rise, volume and reliability. A systematic rectifier power loss analysis and characterization methodology need to be developed for surface mounted ultra‐fast recovery silicon rectifier & silicon carbide Schottky rectifier.

Methodology:

1. Theoretical analysis of voltage multiplier rectifier switching process 2. Circuit simulation & switching process modelling 3. Lab scale conceptual hardware prototype experimental validation


Analyse the operation modes for high frequency voltage multiplier circuit Set up the circuit simulation model for voltage multiplier Develop the methodology to characterize the surface mounted rectifier power loss Build the lab scale conceptual prototype to validate the simulation and analytical results Compare the power loss performance of ultra‐fast recovery silicon diode & silicon carbide

Schottky diode

Collaboration with Industry: Yes, GE China

Contact details: PhD student: Saijun Mao, [email protected] Supervisor: < Dr. Jelena Popovic, [email protected]>

23

Title: Developing hardware for the practical of new course “Advanced Power Electronics”

Type of project: Extra Project

Scope:

For the practical of new MSc course “Advanced Power Electronics” the hardware for the boost converter needs to be developed.

Objectives:

‐ Design a test boost converter with as high efficiency as possible given the constraints.

‐ Component selection, inductor design, testing.

‐ Design of PCB to be used for the practical (see fig 1)

‐ Overall support of practical design.

Contact details: Jelena Popovic [email protected] Bart Roodenburg, [email protected]

Duration:

3 months.

24

Title: 5kW, 70V high efficiency DC‐DC converter, wide output range


Scope: Design and implementation of a 5kW high efficiency DC‐DC converter with vide output range

Problem definition: Design of a 5kW high efficiency DC‐DC converter with the following specifications: Non‐isolated topology, input 80V, output 0 – 70V, max. output current 150A (constant power output), switching frequency 100kHz, efficiency > 98%, low intrinsic EMI generation. Note that the output voltage control needs to be stable at all load conditions, also at very low output voltages. Optionally extended to a bi‐directional version. This 70V converter requires a very different approach, compared to a high voltage (500V) version, due to circuit parasitics.

Methodology: The project will include the following steps: choice of topology, selection of semiconductors, design and testing of prototype.

Collaboration with Industry: Yes, Delta Elektronika

Contact details: Supervisor: J. Popovic, [email protected]

25

Title: Evaluation of a PCB‐implemented Coaxial Shunt Resistor

Type of project: Extra Project or SIP project

Scope:

The scope of this project is to investigate the concept of PCB coaxial shunt resistors to be used for current measurements in high frequency power electronics converters.

Problem definition:

The PCB implemented coaxial shunt resistors provide a cheap alternative to costly and bulky coaxial shunt that can be found on the market. They also offer potential of seamless integration into a circuit of certain simple converter. The project aims to investigate feasibility of implementation of such a structure, and assess its limitations. Two main questions should be addressed: how parasitic inductance and capacitance scales with size (both height and diameter), and how number of sectors affects structure.

Methodology:

To answer the questions of interest a parametric Finite Element Model (FEM) of the structure should be constructed. The provided model will then be validated by measurements in a laboratory.


Provide FEM model Validate the proposed model by measuring on the laboratory setup Assess how parameters of the structure scale with size. How number of sectors affects parameters (such a inductance and capacitance) How asymmetry affects measurement results


Contact details: PhD student: Ilija Pecelj, [email protected] Supervisor: Jelena Popovic, [email protected]

26

Title: 3D coaxial converter integration concept

Type of project: MSc project

Scope:

The scope of this challenging project is to analyse a concept for 3D implementation of power converters based on the coaxial design that minimises circuit parasitics and allows for integrated current measurements.

Problem definition:

With advent of fast wide‐bandgap (SiC and GaN) switches, the circuit parasitics (inductive and capacitive) begin to dominate the circuit behaviour. If we cannot minimise and/or utilise these parasitics using these fast switches can be seen as having a very fast runner with running shoes made of steel. Therefore a circuit layout that minimizes parasitics (parasitic inductance and capacitance) in a power converter, becomes an imperative.

The goal of the project is to investigate a new, concept of 3D circuit design and compare it to the traditional design. Also, a scaling of the proposed structure should be investigated. Since there are many possibilities for the component placement, a design guidelines should be proposed.

Methodology:

The methodology includes implementation of a parametric model in a FEM tool for assessment of field distribution. A scaling of parameters with the size and the number of sectors should be investigated. Finally, one model is selected for implementation for validation of the model. The concept is then experimentally proven on a hardware demonstrator.


Provide FEM (Finite Element Modelling) model of the converter Assess how scaling and number of sectors affects the circuit parameters Propose guidelines for systematic approach when designing a converter Validate model by measurements on a real converter


Contact details: PhD student: Ilija Pecelj, [email protected] Supervisor: Jelena Popovic, [email protected]

27

Title: Design and Optimization of a High frequency CCM PFC Boost Converter Using Gallium Nitride Transistors


Scope:

High frequency power conversion is an ongoing trend in power electronics. Power converters operating at greatly increased switching frequencies could results in largely reduced volume of passive components, and thus high power density can be achieved. To realize high frequency operation while maintaining high efficiency, suitable power semiconductors are needed. The emerging wide bandgap semiconductors are promising candidates for fulfilling the needs.

Problem definition:

The market‐available wide bandgap semiconductors, such as Gallium Nitride (GaN) power transistors and Silicon Carbide (SiC) Schottky diodes, provide potentials for improved performance in a Continuous Conduction Mode (CCM) PFC boost converter: GaN transistors enable very high switching speed, which could largely reduce switching losses even in hard switching conditions; SiC Schottky diodes do not show reverse recovery behaviour, and thus no reverse recovery loss will occur in transistor and EMI performance is improved.

This thesis will focus on optimal design and implementation of a high frequency CCM PFC boost converter for highest possible efficiency utilizing the available GaN transistors and SiC diodes.

Methodology:

Performance of GaN power transistors need to be studied firstly to explore limitations of the transistors in a CCM PFC boost converter environment, which can be done with loss models and measurement results available in the group; then, optimal design of the converter should be carried out with the converter efficiency as the goal; finally, an experimental setup should be built.


To investigate performances of GaN transistors in CCM PFC boost converter To perform an optimal design of a high frequency CCM PFC boost converter To demonstrate the design experimentally

Contact details: PhD student: Wenbo Wang, [email protected] Supervisor: Jelena Popovic, [email protected]

28

D C E & S

DC Systems, Energy


Title: Magnetic design and multi-objective optimization of Dynamic Powering

IPT Systems

Type of project: MSc. thesis

Scope:

Dynamic IPT systems are used for the On-Road powering of Electric Vehicles (EVs). A novel coil design has been

proposed for the purpose of dynamic powering. This design involves repeating a number of triangular sections

on the roadway and a layer of Al below the coils so as to make the flux one-directional.

Problem definition:

A detailed optimization can be carried out in order to optimize different parameters like coupling,

size and weight of the sections.

Methodology:

The first phase of the project involves the validation of the theory developed at the TU Delft using

COMSOL. The next phase involves a multi-objective optimization development for sections of the

coils developed for Inductive Power Transfer.


Consider variables like open-circuit voltage (Voc), short-circuit current (Isc) to calculate the

uncompensated Power (Psu).

Study the variation of coupling along the various displacements possible.

Analyse and build a magnetic model of a suitable pickup and measure the efficiency, power

transferred and coupling.

Perform a multi-objective optimization keeping copper mass, volume as well as Al shield thickness in

mind.

Collaboration with Industry: Yes, HEVO Power, New York

Contact details:

PhD student: Venugopal Prasanth, [email protected]

Supervisor: Pavol Bauer, [email protected]

29

D C E & S

DC Systems, Energy


Title: Experimental analysis of a lab scale Distributed IPT System for Dynamic

On-Road Powering


Scope:

Inductive power transfer (IPT) is the process of transferring power between circuits without

wired interconnects by the process of electromagnetic induction in the near-field.

Problem definition:

A novel coil design based on triangular sections that create N and S poles alternatively along

the roadway is proposed. The thesis is an experimental and FEM validation of the theory

developed.

Methodology:

The first phase of the project involves the validation of the theory developed at the TU Delft

using COMSOL. The next phase involves the experimental validation of the theoretical

studies carried out. The objective is to measure the system parameters (P, η, κ).


Use the existing inverter in the laboratory.

Build a 1m long roadway based on the theory developed. Also, consider the use of Al/Cu shield so as

to restrict the field to a unidirectional one.

Analyse and build a suitable pickup and measure the efficiency, power transferred and coupling.

Validate the magnetic design with FEM simulation (COMSOL).

Collaboration with Industry: Yes, HEVO Power, New York

Contact details:



30

D C E & S

DC Systems, Energy


Title: Experimental and FEM (Magnetic) evaluation of IPT systems

Type of project: SIP 2

Scope:

Inductive power transfer (IPT) is the process of transferring power between circuits without

wired interconnects by the process of electromagnetic induction in the near-field.

Problem definition:

A distributed leakage model of the transformer is proposed and needs experimental

validation.

Validate the double coupling model which proposes a variable leakage picture to both the

primary and secondary.

Methodology:

Use the coils in the laboratory for detailed experimental analysis.

Perform OC tests and make experimental results.


Obtain k1 and k2 of the two coils.

Observe the variation in the individual couplings with vertical displacement of coils.

Observe the variation in coupling when comparing one coil with another.

Validate with FEM simulation (COMSOL).


Contact details:



31

D C E & S

DC Systems, Energy


Title: Foreign object detection in Inductive Power Transfer (IPT) systems


φm(M)

φp(La) φs(Lb)

Primary winding Secondary winding

Air core inductive power tranfer

R1,L1 R2,L2

Scope:

Inductive power transfer (IPT) is the process of transferring power between circuits without wired

interconnects by the process of electromagnetic induction in the near-field. Magnetic fields

permeate through human skin and live objects without a problem. Hence, live object heating and

EMF safety regulations in the presence of magnetic field energy transfer is a major problem.

Problem definition:

Foreign object such as leaves and pieces of iron can result in local heating of these objects and in

case of live objects like cats, it can result in unacceptable leakage fields. To overcome this problem, a

suitable sensing system can be proposed so that the power transferred can be adjusted depending

on the type of object. Here, the emphasis is both on the foreign object detection as well as the power

flow control. A unique solution is to combine Capacitive Power Transfer with Inductive using Electric

Field Proximity Sensing (EFPS).

Methodology:

Perform literature study on different foreign object detection possibilities.

Select a suitable technique considering ease of implementation and control, modularity and

cost.

Build a lab scale prototype and test its operation for both foreign object detection and power

flow.


Proximity sensing of foreign objects during power transfer.

Power flow control and a technique to identify the type of object.


Contact details:



32

Study on Core Materials for 10 MW Direct Drive Superconducting Wind Generators


Scope: Study the core materials suitable for 10 MW direct drive superconducting wind generators in terms of electromagnetic, thermal and mechanical performance.

Problem definition: Superconducting windings are adopted in wind turbine generators to reduce machine size and weight and to increase efficiency. High field excitation allows non‐magnetic materials to replace iron in the core. Non‐magnetic materials, e.g. composites, which significantly change the magnetic circuit, can be lightweight, saturation‐free and loss‐free but expensive and bad for heat transfer. Iron for electrical machines has been very mature, but it is heavy and subject to saturation and iron losses, and iron teeth produces more space harmonics. It is necessary to overview possible core materials, quantify their properties and study their electromagnetic, thermal and mechanical performance for superconducting machines.

Methodology: This research will not involve lab work since a cryogenic environment is not available yet in our lab. Analytical and/or finite element models need to be derived for analysing the electromagnetic, thermal and mechanical behaviours of the core materials in a superconducting generator. Basic knowledge on electromagnetics, heat transfer and force analysis for electrical machines are required and will be developed in this thesis project.

Research Objectives: Find out the possibilities of iron and non‐magnetic materials for superconducting machines, and

quantify their electromagnetic, thermal and mechanical properties used for electrical machines. Compare non‐magnetic materials and iron materials for low‐speed superconducting machines in

terms of electromagnetic, thermal and mechanical performance.


Contact details: PhD student: Dong Liu, d.liu‐[email protected] Supervisor: Henk Polinder, [email protected]

33

Study on DC Field Exciters for Superconducting Synchronous Wind Generators


Scope: Study the excitation systems tailored for superconducting synchronous wind generators, focusing on steady‐state, dynamic and transient performance.

Problem definition: Superconducting windings are adopted in wind turbine generators to reduce machine size and weight and to increase efficiency. In conventional synchronous generators is applied a voltage‐source exciter. However, the zero DC resistance and the high inductance of superconducting windings make voltage‐source exciter very difficult to operate and regulate. Therefore, a current‐source exciter looks more suitable for superconducting wind generators. The possibilities of exciters for superconducting generators have to be compared and the most suitable ones will be examined by analysing their steady‐state, dynamic and transient performance.

Methodology: This research will not involve lab work since a cryogenic environment is not available yet in our lab. Analytical models need to be derived to integrate the current source into the machine model. Analytical models and/or finite element models will be derived to analyse the dynamic and short‐circuit performance. Basic knowledge on power electronic converters as DC current/voltage source is required, but this project will be more on the machine side than on the power electronics side.

Research Objectives: Review the exciters for synchronous generators. Model a current‐source exciter for a synchronous wind generator. Roughly design a current‐source exciter for a 10 MW superconducting wind generator, and evaluate

its steady‐state, dynamic and transient performance.



34

Feasibility Study on Superconducting Armature Winding for 10 MW Superconducting

Synchronous Wind Generators


Scope: Study the feasibility of superconducting armature winding for superconducting synchronous wind generators.

Problem definition: Superconducting machines are adopted to reduce generator size and weight and to increase efficiency. Superconducting field windings have already been extensively proposed for superconducting machines. In this way the size reduction is quite limited unless armature windings are also made superconducting. Superconducting armature windings are, however, not yet recommended because of AC losses, refrigeration difficulties, mechanical limitations and so on . The mechanical limitations have drawn much less attention than the others. This research will study the feasibility of superconducting armature winding especially from the following perspectives: winding distribution, coil shape (end winding shape), and mechanical stress on end winding.

Methodology: This research will not involve lab work since a cryogenic environment is not available yet in our lab. Finite element models will be built for analysing the electromagnetic and mechanical behaviours of superconducting armature winding. The focus is feasibility study, so in‐depth analytical models may not be required except some basic analytical estimations.

Research Objectives: Review the possibilities of conventional armature windings and superconducting armature windings. Propose a superconducting armature winding design for a 10 MW superconducting generator. Model and evaluate the electromagnetic performance of the superconducting armature winding. Model and evaluate the mechanical performance of the superconducting armature winding.



35

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36

D C E & S

DC Systems, Energy


Title: Fault Modes in Wind Turbine Generator Systems


Background

Even though the reliability of wind turbines has improved over time, they still see failure rates of

more than one failure per turbine per year. Of these failures, the drivetrain is a source of problem

and fails often. It is evident that addressing the failure rates of the drivetrain could have a major

impact on the overall availability, and hence the Cost of Energy, of the wind turbine.

One of the ways to achieve increased availability is by incorporating fault tolerance in the design.

Therefore, if a component fails, the system can continue operation.

Problem definition

The knowledge about fault mode behaviour of a generator system is important from the point of

fault tolerant control. The project deals with the identifying the failure modes in these systems and

investigating the behaviour of the generator system under such failure conditions. Some of the

failures to be considered are – Winding Short Circuit, Inverter switch open circuit, inverter switch

short circuit, DC link failure etc.

The study can be extended to understanding fault diagnosis, which is important from the point of

view of reconfiguring the system to be fault tolerant.

Methodology

The project will require the building of generator system models and simulating failure modes.

Research Objectives

Investigate the types of failure modes occurring in wind turbine generator systems.

Investigate system response to these failure modes.

Investigate Fault Diagnosis on the basis of the response to failure modes.

Necessary Background: AC Machines, Control of Electrical Drives

Contact details:

PhD student: Udai Shipurkar, [email protected]

Supervisor: Dr.ir. Henk Polinder, [email protected]

37

D C E & S

DC Systems, Energy


Title: Investigation of the pole-pair combinations of the Brushless Doubly-Fed

Induction Machine for wind turbine application


Scope: The brushless doubly-fed induction machine (BDFIM) has an attractive potential to be a new

variable speed wind generator due to its higher reliability and increased fault handing capabilities.

Two stator windings with different pole-pair numbers have no direct-coupling, but cross-coupling

through a special nested-loop rotor. For the purpose of the operation principle demonstration,

several pole-pair combinations have been investigated for a small-scale prototype. However, for the

megawatt wind turbine application, the determination of the pole-pair combination should not only

consider the performance, but also the economic costs.

Problem definition: Investigate the selection of the pole-pair combination in BDFIM for the megawatt

wind turbine application.

Methodology: Finite element (FE) model is performed to calculate the magnetic field distribution and

the machine performance (core losses, efficiency etc.). Multi-objective optimization combined with

the FE model is performed to investigate the trade-off between different pole-pair combinations in

the BDFIM.


Build the FE model for the optimization purpose.

Develop a FE based multi-objective optimization using normal GA or PSO etc.

Investigate the trade-off between different pole-pair combinations in BDFIM for wind turbine

application.

Collaboration with Industry: No.

Contact details:

PhD student: Xuezhou Wang ([email protected])

Supervisor: Henk Polinder ([email protected])

38

D C E & S

DC Systems, Energy


Title: Prediction and validation of core losses in Brushless Doubly-Fed Induction

Machine


Scope: The brushless doubly-fed induction machine (BDFIM) has an attractive potential to be a new

variable speed wind generator due to its higher reliability and increased fault handing capabilities.

However, the undesirable spatial harmonics in the air-gap magnetic field result in a bigger core losses

comparing with the normal doubly-fed induction generator (DGIG). The core losses calculation is

more complex because there are two stator windings with different pole-pair numbers in BDFIM.

Therefore, it is important to develop an appropriate model for the prediction of the core losses and

validate it in a small-scale prototype during the design of the BDFIM.

Problem definition: How to predict the core losses of the BDFIM and how to measure them in the

prototype.

Methodology: Finite element (FE) model can be performed for an accurate calculation of the

distribution of the magnetic field, as well as the core losses. Laboratory work on the prototype will be

involved for the validation of the model.


Literature survey on the modelling and the validation of core losses.

Build an appropriate FE model for the core loss prediction of the BDFIM.

Develop a way to measure the stator and the rotor core losses in BDFIM.


Contact details:



39

D C E & S

DC Systems, Energy


Title: The influence of the pole-pair combination on the torque ripple and

unbalance magnetic pull (UMP) in Brushless Doubly-Fed Induction Machine


Scope: The brushless doubly-fed induction machine (BDFIM) has substantial benefits comparing with

the normal doubly-fed induction machine. However, there are amounts of undesirable spatial

harmonics in the air-gap magnetic field due to the fact that the special nested-loop rotor needs to

couple both the power winding and the control winding simultaneously. A bigger torque ripple could

be expected because of the rich harmonics and it is interesting to investigate the influence of the

pole-pair combination on the torque ripple. In addition, the unbalance magnetic pull (UMP) could

also be an issue with respect to the different pole-pair combinations.

Problem definition: How about the influence of the pole-pair combination in the BDFIM on the

torque ripple and the UMP.

Methodology: Time-step finite element (FE) model is accurate to look into the detailed torque and

UMP characteristic. Part of the work can be validated by the prototype.


Build the FE model including the torque (and UMP) calculation in the post-processing using

Maxwell’s stress tensor and/or Virtual work method.

Investigate the influence of the pole-pair combinations on the ripple (and UMP).

Part of the work can be performed on the prototype for the validation of the model.


Contact details:



40

D C E & S

DC Systems, Energy


Title: DC hubs as dc breakers within an MTdc network


Conceptual design of an offshore dc plug.

Scope: This thesis focuses on the application of multi-port dc-dc converters for the isolation

of dc faults within a multi-terminal dc network.

Problem Definition: MTdc voltage-source converter-based networks are vulnerable to DC

faults and lack of adequate protection has proven to be a significant problem preventing

them from expansion. Several measures have been suggested in the literature, regarding

design of dc breakers and control strategies for fast and reliable detection and isolation of

faulty lines, and some prototype breakers have been designed (ABB, Alstom). However,

breaker use is not yet extensive and the dc fault protection topic is highly challenging.

DC hubs can be defined as multi-port dc-dc converters with the ability to interconnect

different HVdc systems which operate at different voltage levels, control the power on each

dc line and facilitate the connection and disconnection of any dc line without affecting the

operation of the grid.

Methodology: This thesis mainly involves simulations with Matlab/Simulink tools and PSpice

designer.


Analyse the dc fault dynamics within meshed MTdc network;

Develop simulation models to study, in as much detail as possible, the dynamic

behaviour of the dc hub in case of dc contingencies;

Develop a methodology for the dc fault protection of an MTdc network using dc

hubs.

Contact details:

Daily advisor: Epameinondas (Minos) Kontos, MSc. , LB 03.690, [email protected];

Supervisor: Dr. Ir. Pavol Bauer, LB 03.600, [email protected]

41



D C E & S

DC Systems, Energy


Title: DC-DC converters for HVdc integration: Design and Control


Conceptual design of an offshore dc plug.

Scope: This thesis aims at defining the application possibilities of dc-dc converter designs in a

multi-port design and evaluate the impact of the technology choice within a multi-terminal

HVdc (MTdc) network.

Problem Definition: As more point-to-point HVdc connections are proposed or are under

construction, it is foreseen that in the future projects that operate at different voltage levels

would need to get interconnected to form large and more stable dc grids. Therefore, there is

the research opportunity to study the solution of a dc interface to achieve this transition

from dc point-to-point connections to dc grids.

The role of an interface could be played by multi-port dc-dc converter stations which can be

placed either onshore or offshore and will be able to accommodate the interconnection of

HVdc projects. These multi-port converters are called dc hubs and could operate as dc

"plugs". But how can these be realized?

Methodology: This thesis mainly involves simulations with Matlab/Simulink tools and PSpice

designer.


Perform a survey on different dc-dc converter schemes and specify the requirements

of a multi-port design;

Develop simulation models to analyse in as much detail as possible the dynamic

behaviour of the dc hub;

Evaluate the impact of the technology choice when it comes to operation and control

during normal operation and contingencies within an MTdc network.

Contact details:



42



D C E & S

DC Systems, Energy


Title: Design and construction of a lab-scaled MMC-VSC converter


Alstom HVDC SINE submodule.

Scope: The goal is to design and construct a low-voltage low-power MMC-VSC converter in

the laboratory to verify with the best accuracy the real full-scale HVdc converter behaviour.

Problem Definition: To design the MMC converter we first need to define the dc voltage level,

as well as the current rating of our application. The existing equipment in the lab is rated at

±350 V and 7 A rated current.

The next requirement is to achieve a low harmonic distortion. Theoretical calculations are

performed to define the number of levels required to achieve this. At a next stage, we need

to define the specifications of the necessary components. It is important that our design

assumptions are backed up by the specifications of the HVdc network we want to simulate.

Moreover, depending on the voltage levels we want to achieve with the MMC, we need to

define the control structure and the communication system.

Methodology: This thesis comprises both a simulation and a testing phase. The approach to

be followed is to construct one fully-operational module for testing. As soon as this phase is

dealt with, the construction of more submodules will be done in the same way and for each

newly added conversion level, the MMC will be tested to verify its operation.


Build a fully-operational MMC converter;

Verify the control of the converter applying different advanced control strategies;

Compare the MMC test results with the simulation results made in Matlab/Simulink.

Contact details:



43



D C E & S

DC Systems, Energy


Title: Susceptibility of oil-impregnated cellulosic materials to partial discharges


Scope: The current work is aimed at optimization of the impregnation process of cellulosic materials

used in high-voltage (>400 kV) high-power transformers. In particular, it is necessary to find when

such materials are completely impregnated and will not show partial discharges (PD) during testing.

Problem definition: To ensure reliable operation of a transformer for the desired period of e.g. 40

years, it must be ensured that the transformer insulation is PD free. It has been shown that perfectly

dry materials will not show any PD activity. However, during the construction process of a

transformer, its insulation is exposed to ambient air for the period of 24 hours. During that period,

the insulation will absorb moisture what finally leads to increased dielectric losses and PD activity

causing a breakdown of an insulation. After the impregnation of the insulation is completed, the

transformer is left for a period of multiple days so that the moisture from the wood can be

tra sported to the oil. This period is called sta di g ti e . I the e d, the opti izatio of the standing time will help to optimize the production process.

Methodology: The work will be focused on investigation the PD activity in samples of oil-impregnated

insulation consisting of both paper and pressboard with respect to the moisture content. More

specifically, the samples will be moisturized in a controlled way, impregnated with oil and subjected

to PD testing. The PD inception voltage (PDIV) in function of standing time is of interest.


Study the moisture ingress into the cellulosic materials

Determine the changes of PDIV in the insulation samples with respect to the moisture

content and standing time

Propose the minimum standing time based on the research outcomes.

Collaboration with Industry: Yes, Royal SMIT Transformers Nijmegen

Contact details:

Łukasz Ch ura: [email protected]

Paul van Nes: [email protected]; Armando Rodrigo Mor: [email protected]

44




D C E & S

DC Systems, Energy


Title: Decision support for the asset manager – knowledge of the status

of high-voltage instrument transformers


Scope: The major part of paper

insulated equipment installed in transmission and distribution network is 30+ years old. During operation,

the insulation of a component is stressed electrically, thermally and

mechanically. This leads to the insulation degradation and by-products arising (e.g., gases and

water) which endanger reliable operation of the component. In

addition, external operational conditions play a role since the moisture might ingress into the component. Obtaining the knowledge

about the condition and reliability of the oil-impregnated paper insulation in essential for the assessment of residual life of a component

Problem definition: Although there has been an extensive work done on investigation of

material ageing, still there is little information on the influence of material degradation, arising by-products and foreign contaminants on the failure probability of an asset. Therefore, the following questions have to be answered when considering the best possibility

for condition assessment of paper insulated assets: -which parameters and testing techniques have to be taken into account

-how to interpret the measured parameters, this includes the knowledge of insulation material together with its withstand capabilities as well as the limit values of measurable parameters.


Information about the best measuring techniques to be applied

Information about the values and trends of diagnostic parameters along the ageing

period when the degradation progresses and contamination increases, in particular in

the moment preceding the failure.

Advices on the equipment status and actions to be taken.

Collaboration with Industry: Yes, TenneT

Contact details:

Łukasz Ch ura: L.a.ch ura@tudelft. l Armando Rodrigo Mor: [email protected]; Paul van Nes: [email protected]

45



D C E & S

DC Systems, Energy


Title: Development of a High-Sensitivity Measuring System for Defect

Detection in Epoxy Based Material


Scope: The scope of this research project is to develop a high-sensitivity measuring system to detect

small defects in epoxy based insulated materials.

Problem definition: Nowadays, solid insulating materials as epoxy based materials are used in high

voltage assets because they have some advantages over liquid insulated systems. When possible,

solid insulation is preferred in outdoor installations because there is no possibility of spills in case of

leakage, which makes solid insulation a more environmentally friendly installation. However, the

manufacturing of big pieces of epoxy based components is a difficult task. Small defects present in

the bulk epoxy based material are a risk for the insulation because of the mechanical and electrical

working stress conditions of the insulation.

Cavities and small cracks can appear in the insulating material during the manufacturing process that

later on can lead to a failure of the insulation. Due to the novelty of such insulating systems, there is

no standard defining the suitable tests for epoxy based insulating systems in high voltage

components. It has been identified that some of these defects can be detected by means of partial

discharge tests when they are in areas where the electric field is relatively high. However, defects in

low on medium stressed electric field areas are much more difficult to detect and can easily lead to

breakdown. Therefore, a new methodology to trigger the partial discharge activity is needed in order

to increase the sensitivity of the detection system even in areas standing low or medium electric

fields.

Methodology: Research experiments to determine the influence of different parameters triggering

partial discharges in epoxy based insulating materials have to be investigated firstly. The influence of

temperature, transients, electromagnetic impulses, mechanical impulses and other external factors

that could trigger or accelerate partial discharges have to be investigated. Extensively usage of

laboratory experiments is expected in order to check and compare the feasibility of the proposed

methodologies to increase the sensitivity of the measurements. On the other hand, epoxy samples

with artificial representative defects must be fabricated and tested.


To identify the different types of defects present in epoxy based solid insulation.

To produce samples with artificial representative defects.

To identify the different parameters that influence and trigger partial discharges.

To develop laboratory tests to check the influence of the identified parameters in electrical

tests in order to improve the sensitivity of the measurements.

Collaboration with Industry: Yes, Prysmian Cables and Systems hic

Contact details:

Dr. Armando Rodrigo Mor, [email protected]

NOTE: this master´s thesis project is subjected to a non-disclosure agreement.

46

D C E & S

DC Systems, Energy


Title: Dielectric Stresses and Strength Requirements for Substation Secondary Equipment.


Scope: The scope of this project is to investigate about failures in substation secondary equipment and propose

mitigation techniques or specifications to increase the reliability this equipment.

Problem definition: Nowadays electronic and digital equipment forms the state-of-the-art technology for

protection, regulation, control, auxiliary, telecommunication and other functions in HV and MV substations, as

well as in other plants. Most secondary equipment is supplied from LV DC-sources. These sources as well as

some secondary equipment are equipped with back-up power supply from batteries and capacitors, mostly so-

called elcons . The energy for the DC-sources is coming from a LV AC-network and an electronic converter

takes care for the conversion from AC to DC. The conversion introduces harmonics and spikes into the voltage

profile at the DC-side, thus introducing additional dielectric stresses to the batteries, capacitors and other

insulated parts of the secondary equipment.

Also other parts of the secondary equipment are stressed by discontinuous voltages and currents; parts used

for the sensoring functions, for the signal treatment, for drives, etc. Other stresses for the secondary

equipment, especially for the insulation are environmental stresses, like humidity, high and low temperature,

vibrations, pollution, moisture, etc.

Nowadays secondary equipment is as important as primary equipment and corresponding requirements with

respect to reliability and availability have to be put forward. Still, many problems, especially with ageing

secondary equipment, are reported. The vulnerable components are, among others, the batteries and the

capacitors. Dielectric stresses are most probably the cause of these problems. Mitigation possibilities in the

specification, in the installation conditions, in inspection and diagnostic techniques, in maintenance and

replacement policies are needed.

Methodology: A scientific investigation of the dielectric problems that occur in the aged secondary equipment

will be the first step to quantify the problem and to find trends. The various possible stress parameters of

influence have to be collected and the dielectric strength as function of the age and environmental conditions

have to be studied.

Following the material research, a suitable and feasible way to assess the insulation degradation of the LV

insulating materials will be described. The research will end with the definition of or the development of

suitable diagnostic techniques, of adequate specifications for secondary equipment and methods to extend the

life of components.


To define the working conditions of secondary equipment

To elaborate the failure mode analysis of basic secondary equipment

To determine the most critical components and working conditions

DCE&S DC Systems, Energy Conversion & Storage

To determine suitable diagnostic techniques to evaluate the risk of failure of such components

To establish extra component or installation specifications if required

Collaboration with Industry: Ksandr

Contact details:


47

D C E & S

DC Systems, Energy


Title: Development of a Nobel Space Charge Measuring System for Characterization of High

Voltage DC Materials Type of project: MSc thesis

Scope: The scope of this research project is the development of a novel space charge measurement system

with enhanced sensitivity and spatial resolution for the characterization of high voltage DC materials.

Problem definition: HVDC networks are widely increasing their presence in the transmission network due to the

new developments and achievements of HVDC power converters. Therefore, new insulating materials need to

be designed and characterized under high DC electric fields. One critical parameter in HVDC insulation is space

charges. Space charges appear inside the insulation as a consequence of microscopic defects of the insulating

material and elevated electric fields. These space charges move in time along the insulation modifying and

distorting the electric field inside the insulation. As a consequence, when the distortion of the electric field

reaches the limit of the material the insulation breaks down producing the failure of the component.

Space charges develop inside the bulk of the insulating material. The space charges remain in a quasi-static

position and move slowly along the insulation. Therefore their detection is extremely difficult. The PEA or pulse

electro-acoustic was develop in the past to detect acoustically space charges in small specimens or short and

small HVDC cables. The method applies HVDC to the sample while at the same time a fast pulse in the range of

nanoseconds is superposed producing a transient between the electrodes that moves the charges inside the

insulation. This small movement of the charges inside the insulation generates a mechanical vibration that can

be detected with piezoelectric sensors and high gain amplifiers.

Because the crosstalk interference of the applied fast pulse with the measured signal from the piezoelectric

sensor, the analyzed signal needs to be filtered, averaged, and deconvoluted to reconstruct the original signal

form which physical interpretations are obtained. In order to achieve a good spatial resolution, the injected

electrical pulse must be as narrow as possible and efficiently injected in the sample. The test setup has not only

to facilitate the electrical pulse injection, but have a good acoustical behaviour in order to properly measure

the small displacement of charges inside the material. Problems arise when measuring thick samples or cables

because of the acoustical attenuation of the samples and a more difficult electrical pulse injecting. Therefore,

improved setups and more sensitive and broadband measurements have to be developed to improve the

material characterization.

Methodology: Good understandings of space charge creation and behaviour have to the achieved prior to the

development of the new setup and measuring system. Strong knowledge about the mechanical and electrical

properties of all the involved elements must be gained in order to describe and improve the measurements.

Advanced acoustic measurements based in modern techniques should be considered as a replacement of the

piezoelectric in order to improve the sensitivity and bandwidth. A reference test setup and sample have to be

defined in order to calibrate and compare the results using different measurement techniques and setup

configurations.


To understand space charge formation and effects in HVDC insulation materials

To understand the pulse electro acoustic method used for space charge measurements

To understand the acoustic and mechanical properties of the insulating materials

To create acoustic and electrical models of the samples and setups

To improve the sensitivity and bandwidth of the measurements

To compare by means of experiments the different measurement techniques


Contact details:


NOTE: this master´s thesis project is subjected to a non-disclosure agreement.

48

D C E & S

DC Systems, Energy


Title: : Developing Models for a Smart Grid Table

Type of project: Internship

Figure 1: Watt Connects interactive table

Scope: Energy transition stakeholders such as governments, technology suppliers and utilities have a clear

need for understanding the complex interactions of components and parties in (future) smart grids. Watt

Connects has an interactive table with a grid model, 10 inputs and state-of-the-art visualization. The system is

composed of a master computer and several satellite computers operated by the users. To allow modelling of

more topics (such as energy-neutral districts) and a flexible expansion roadmap, a new model and framework

must be constructed.

Problem definition: The objective of this assignment is to develop a modular energy model for e.g. city

districts. The model to be developed has to perform the energy balance of a series of devices connected

(houses, photovoltaic systems, electric cars, micro wind turbines, heat pumps, storage, etc.). It has to provide

functionalities like energy neutral homes over the year. This model would not require the use of an electrical

grid. Modularity is essential: accommodating future expansions, by way of additional or refined functionality

such as a more detailed submodel of a house or a new type of generator or load, needs to be easy. The model

will be implemented in a technical framework that will handle 1-10 inputs, visualization, data processing etc.

Methodology:

- Programming language: Python, Java or Matlab

- Good level of speaking and writing in English is required.


- Programming and testing of the model framework

- Documenting code and functionality: code comments, developers manual, users manual

- Working with technical / content modelling experts / interns on integration of modelling capability

Collaboration with Industry: Yes, DNVGL

Contact details:

Martijn Huibers – [email protected], Ballard Asare-Bediako – [email protected]

Laura Ramírez, [email protected], Paul Bauer, [email protected]

49

D C E & S

DC Systems, Energy


Title: Information Technology Framework for a Smart Grid Table


Figure 1: Watt Connects interactive table

Scope: Energy transition stakeholders such as governments, technology suppliers and utilities have a clear

need for understanding the complex interactions of components and parties in (future) smart grids. Watt

Connects has an interactive table with a grid model, 10 inputs and state-of-the-art visualization. The system is

composed of a master computer and several satellite computers operated by the users. To allow modelling of

more topics (such as energy-neutral districts) and a flexible expansion roadmap, a new model and framework

must be constructed.


The objective of this project is to develop the essential functionalities of the Watt Connects paradigm: a

framework around a next-generation modular and flexible smart grid model, having 1 to 10 input units, an

output screen and an output table (projectors onto white surface). Those functionalities are:

- Expandable Server + Client structure on a local network.

- Database to store data (general model with a dummy test scheme) connected with the server + client

structure previously mentioned.

- Visualization module (Special kind of Client)

- Executable on a single computer

- Dummy calculation framework.

Collaboration with Industry: Yes, DNVGL

Contact details:

Martijn Huibers – [email protected], Ballard Asare-Bediako – [email protected]

Laura Ramírez, [email protected], Paul Bauer, [email protected]

50

D C E & S

DC Systems, Energy


Title: Inductive Charging of passenger vehicles in Rotterdam: technical

challenges, safety and efficiency


Scope: Stadsregio Rotterdam, Gemeente Rotterdam and Stichting E-laad realize induction charging in

the public space of Rotterdam this year. A master student is invited to join them. It’s a hands-on

project at full speed: the project starts this year. At the end of this year, test facilities will already be

in action. The project is about testing new technologies, gaining technological expertise and

understanding user behaviour.

Problem definition: The focus of the student is on technical challenges of inductive charging in public

space, for instance safety measures and standardisation issues. This is demanding, while the market

and the technology is rapidly changing.


What is required if one charger can work with multiple car type?

How to deal with foreign objects and inductive charging?

How would this connect to existing charging infrastructure?

Collaboration with Industry: Yes, EVCon3sul.

Contact details:

Roland Steinmetz, [email protected]

Paul Bauer, [email protected]

Start date: Spring 2015

51


DCE&S

DC Systems, Energy

Conversion & Storage Title: Energy storage in electric rolling stock Type of project: MSc thesis Scope: At NedTrain RO Haarlem rolling stock (railways) are refurbished and overhauled. The

refurbishment is executed in the midterm of the lifecycle (approximately after 20 years). For the

main refurbishment projects a lot of engineering activities has to be done. State-of-the-art

components need to be integrated in trainsets which are 20 years old. The new and old systems

need to work together after the process. Both, the production plant and the engineering department

are located on the same premises which result in lively debates.

Problem definition: In rolling stock that is currently operated regenerative braking is applied

together with classic braking based on mechanical friction. When the train brakes regenerative, the

traction motor start to work as electrical generator. The generated energy is supplied to the

catenary and hopefully consumed by another trainset. The regenerated energy cannot be supplied

to the electricity grid as the catenary provides a 1500 V DC voltage. In case the energy is not

consumed elsewhere, the voltage rises quickly and braking resistors on roof of the trainset are used

to dissipate the excessive amount of energy. Research Objectives:

Investigate the different options energy storage provide when located inside rolling stock. Investigate the appropriate size of the energy storage and the type of technology which is

most suitable. A control strategy needs to be devised and tested by means of simulation.

Collaboration with Industry: Yes, Nedtrain.

Contact details:

Dr. ir. J.F. Baalbergen, [email protected] Ing. W.J. de Wit, [email protected] Paul Bauer, [email protected]

52

DCE&S

DC Systems, Energy

Conversion & Storage Title: Electricity Market Simulation Tool Development Type of project: MSc thesis Scope: The aim of the master thesis work is to validate and calibrate the MATLAB-based market

simulation tool, by investigating the assumptions that are being used in the current tooling

development. Bug fixes in MATLAB are also expected during the thesis internship. A Flow-Based

market mechanism needs to be developed and implemented in the tool as well. Problem definition: The market tool at E-Bridge is based on the current ATC market coupling

mechanism, and is able to optimize the electricity market outcome (e.g. net position, zonal prices,

cross-border exchanges, etc) based on given inputs (e.g. installed capacity, fuel prices, transmission

capacity, wind power infeed, network constraints, etc). The market tool is developed in MATLAB. In

the current version of the tool, many assumptions have been applied. These assumptions have

certain impacts on the simulation results, and thus need to be carefully evaluated and validated. It is foreseen that the EU energy market is gradually moving from an ATC to a Flow-based (FB)

mechanism. The implementation of the FB market mechanism in the Matlab tool is an additional

task. Methodology: The thesis work involves MATLAB scripting and simulation. Research Objectives:

Validate and calibrate the market simulation tool Bug fixes in the current MATLAB scripts Implementation of Flow-based market mechanism

Collaboration with Industry: Yes. The qualified thesis student will be supervised by Dr. Zongyu

Liu, the consultant who built the market tool, in close cooperation with other experts within the

company. Prerequisites: The qualified master student is expected to have an electrical power engineering

and/or mathematics/optimization background. Good command of MATLAB scripting is essential.

Communication in English is a must, knowing Dutch is certainly a plus. The internship requires full-

time (40 hours/week) working at E-Bridge Consulting B.V. in. Oosterbeek. Remuneration: A fixed compensation of 400 euros per month Working location and contact details: E-Bridge Consulting B.V. is based in Oosterbeek, the

Netherlands. For more information about E-Bridge Consulting B.V., please visit http://www.e-

bridge.com/.

Contacts:

Zongyu, [email protected]. or at +31 26 700 9792.

Paul Bauer, [email protected]

53

http://www.e-bridge.com/

http://www.e-bridge.com/

DCE&S

DC Systems, Energy

Conversion & Storage Title: Building a home energy management system and implementing it at

test locations Type of project: Internship Scope: This project entails the integration of radio-controlled radiator valves (steered by a simple

programmable computer, the Raspberry Pi 2) into a home energy management system. It will

involve the construction of learning algorithms comparable to those used by systems such as the

NEST (www.nest.com) but with the ultimate aim of a much simpler and lower-cost solution working

from local rather than cloud-based data (possibly using a peer-to-peer Cassandra network).

Furthermore, while the NEST only controls the main heating system (e.g. gas boiler), this system will

enable energy saving by control of radiator valves alone.

The main goal of this project is to prove that substantial energy savings are achievable by such a

system.

The system would then be tested at a small number of representative locations, and the data

generated would then be collated and used for further learning and analysis. In close cooperation

with a mobile app developer, an interface will then be designed so that the system can be

controlled from a smartphone. Collaboration with Industry: Yes, Shell

Contact details:

Dr. Alice Elliott, Shell. +31-6-55123393, [email protected] Paul Bauer, [email protected]

54

DCE&S

DC Systems, Energy


Title: De elop e t a d testi g of a hite box ther al a d power consumption model of the EcoGenie house

Type of project: Internship Scope: Following a literature review of one-dimensional physical models for heat transfer and power

consumption, the student should develop an accurate model including all relevant environmental

variables, in particular the dependence of droughts through the building on wind speed and

direction.The model will be validated and tested against data (historical and real-time) from the test

house in the Hague. The desired end result is a model which enables us to forecast energy

consumption (kWh) over time, up to 72h ahead. Collaboration with Industry: Yes, shell

Contact details:

Dr. Alice Elliott, Shell. +31-6-55123393, [email protected] Paul Bauer, [email protected]

55


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