Nicholas Hoeft
MS Graduate, 2020
Thesis: POWER ELECTRONIC ARCHITECTURE FOR MULTI-VEHICLE EXTREME FAST CHARGING STATIONS.
Abstract: Electric vehicles (EV) are quickly gaining popularity but limited driving range and a lack of fast charging infrastructure are preventing widespread use when compared with gas powered vehicles. This gave rise to the concept of multi-vehicle extreme fast charging (XFC) stations. Extreme fast charging imposes challenges in the forms of power delivery, battery management, and energy dispatch. The extreme load demand must be handled in such a way that users may receive a timely charge with minimal impacts on the electric grid. Power electronics are implemented to address these challenges with highly power dense and efficient solutions. This work explores a power electronic architecture as one such solution. The system consists of three parts: a cascaded H-bridge (CHB) active rectifier that interfaces to a medium voltage (MV) grid, a dual active bridge (DAB) based solid state transformer (SST) that provides isolation and forms a low voltage DC (LVDC) bus, and full bridge DC-DC converters configured as partial power converters (PPC) that interface with the vehicle battery.
BS in EE and Electronics Engineering from University of Wisconsin – Milwaukee, Milwaukee, WI, 2017.
Assistant in Research
Florida State University
Mark Vygoder
MS Graduate, 2020
Thesis: A HARDWARE-IN-THE-LOOP PLATFORM FOR DC PROTECTION
With the proliferation of power electronics, dc-based power distribution systems can be realized; however, dc electrical protection remains a significant barrier to mass implementation dc power distribution. Controller Hardware-in-the-loop (CHiL) simulation enables moving up technology readiness levels (TRL) quickly. This work presents an end-to-end solution for dc protection CHiL for early design exploration and verification for dc protection, allowing for the rapid development of dc protection schemes for both Line-to-Line (LL) and Line-to-Ground (LG) faults. The approach combines using Latency Based Linear Multistep Compound (LB-LMC), a real-time simulation method for power electronic, and National Instruments (NI) FPGA hardware to enable dc protection design with CHiL. A case study is performed for a 1.5 MW Voltage Source Rectifier (VSR) under LL and LG faults in an ungrounded system. The deficiency in real-time simulation resolution of Commercial-off-the-Shelf (COTS) for dc fault transients is shown, and addressed by using LB-LMC RT solver inside NI FPGA hardware to achieve 50 ns resolution of dc fault transients.
BS in EE and Physics from University of Wisconsin – Milwaukee, Milwaukee, WI, 2017.
Rounak Siddaiah
MS Graduate, 2019
Thesis: DERIVATION OF POWER SYSTEM MODULE METAMODELS FOR EARLY SHIPBOARD DESIGN EXPLORATIONS.
Abstract: The U.S. Navy is currently challenged to develop new ship designs under compressed schedules.
These ship designs must necessarily incorporate emerging technologies for high power energy conversion in order to enable smaller ship designs with a high degree of electrification and next generation electrified weapons. One way this challenge is being addressed is through development of collaborative concurrent design environment that allows for design space exploration across a wide range of implementation options. The most significant challenge is assurance of a dependable power and energy service via the shipboard Integrated Power and Energy System (IPES). The IPES is largely made up of interconnected power conversion and distribution equipment with allocated functionalities in order to meet demanding Quality of Power, Quality of Service and Survivability requirements. Feasible IPES implementations must fit within the ship hull constraints and must not violate limitations on ship displacement. This Thesis applies the theory of dependability to the use of scalable metamodels for power conversion and distribution equipment within a collaborative concurrent design environment to enable total ship set-based design outcomes that result implementable design specifications for procurement of equipment to be used in the final ship implementation.
BE from Visvesvaraya Technological University, Bangalore, India, 2015.
Jacob Gudex
MS Graduate, 2019
Thesis: EXPLORING METHODS FOR STUDYING RECOVERABILITY OF SHIPBOARD ELECTRICAL POWER DISTRIBUTION SYSTEMS.
Abstract: Advancement of the technology included on ships, is changing the nature of loads installed on ships. Not only are there more loads than installed power generation, but advanced electrically powered weapons and sensors are changing the profile of the installed loads. These are challenges for future shipboard power systems design. Challenges which must be solved with careful distribution system planning, energy storage integration, and selection of individual power electronic converters within the ship. Different topologies and distribution systems have differing fault isolation and recovery (FIR) capability sets, which affects ship survivability. Furthermore, different FIR capability sets, operate at different speeds. The speed of a system’s survivability functionality dictates the amount of energy storage needed. A goal of this work is to enable such topological comparisons.A challenge of making such topological comparisons is simulating shipboard power distribution systems. For the purposes of FIR the simulation must have accurate grounding and realistic cabling to enable study of line to line and line to ground faults in a floating system. This means the simulation must not only have differential mode behavior but accurate common mode behavior. As well as the challenge presented by the length of time required to simulate large systems by conventional offline simulation methods. By finding means to reduce simulation run times, via the use of real time simulations methods. While keeping in mind that each module has an effect on FIR efforts, which implies that the controls of each sub-system must be capable of enabling FIR topological comparisons. In this work a set of simulations of a realistic ship auxiliary power system with full switch models, including medium voltage and low voltage distribution, were developed and tested. This lays the ground work for future topological comparisons enabled by the simulation methodology and state machine based controls.
BS in EE from University of Wisconsin – Milwaukee, Milwaukee, WI, 2017.
Associate of Arts and Sciences, Mathematics and Engineering, UW-Milwaukee at Waukesha
Anna Brinck
MS Graduate, 2018
Power and Controls Engineer
Nhu Energy, Inc.
Fatima Nasiri
MS Graduate, 2019
Thesis: DEVELOPMENT OF A RESONANT HIGH POWER CHARGING STATION FOR FLEET VECHICLES
Abstract: Conventional vehicles chargers are based on plugging the car battery using wire to the electricity grid through some conversion levels. In general, this system is an interface between the AC grid and the battery which requires DC voltages.
The focus of this research is on wireless power charging technology. The wireless configuration benefits the system by providing electric isolation between transmitter and receiver side, and by making the charging process more convenient for the users.
One major drawback of the wireless charging systems in compare to the conventional system is the lower efficiency of these systems. The resonant high power charging configuration of this study is designed to tackle this problem by enabling soft switching to minimize the switching loss.
In this research a resonant LLC configuration is used for the EV charging application. The configuration and the step by step design of the resonant circuit is illustrated and analyzed. Also, other different topologies of the wireless charging systems have been introduced and compared with the proposed topology. The converter is modeled and simulated for different modes of operation. The optimal frequency selection which is dictated by the resonant circuit and magnetic design is obtained based on the mathematical model of the circuitry. The simulation results show that the designed converter improves the efficiency significantly using the resonant wireless charging configuration.
Senior Power Conversion Engineer
Eaton
Jonathan Hajime Itokazu
MS Graduate, 2019
Thesis: HIGH FREQUENCY CONSTRAINTS ON THE LAYOUT OF WIDE BAND GAP-BASED POWER ELECTRONIC ASSEMBLIES WITHIN SHIELDED ENCLOSURES.
Abstract: Since its integration into power electronic converters, the value proposition of wide band
gap semiconductors has yet to be holistically realized due to the high frequency effects associated with increased switching speeds. The United States Navy’s Smart Ship System Design (S3D) platform enables the investigation of wide band gap-based devices in shipboard Medium Voltage Direct Current (MVDC) Integrated Power and Energy Systems (IPES) through the use of metaheuristic model-based scaling laws. These physics-based scaling laws are produced from a virtual prototyping approach which takes into account the discrete building blocks associated with multi-cell based power conversion and distribution equipment and can be used to predict size, weight, losses, cost and reliability. In present practice, the discrete building blocks consist of power electronic assemblies laid out and enclosed within shielded enclosures. In an effort to incorporate the high frequency effects associated wide band gap-based Power Electronic Building Blocks (PEBB) into the virtual prototyping approach, a mathematical model which captures the high frequency effects is formulated in this thesis.
BS in Electrical and Electronics Engineering, University of Wisconsin-Milwaukee, 2016.
Graduate Research Assistant and Lecturer University of Hawaii, Manoa
Amin Khanlar
MS Graduate, 2018
Thesis: RESISTIVE SOLID STATE PROTECTIVE DEVICE
Abstract: This thesis describes and explains different fault to characterize fault specifically for DC distribution systems and DC Microgrids fed by synchronous generators. This will result in a testbed for static and intermittent line-to-line faults, and in future work, various types of ground faults. Automaton allows for repeated testing at various voltage levels and precise control over intermittent fault generation. The fault generator is implemented with an IGBT H-bridge topology. Its physical implementation and benefits are described. Experimental results are shown for static line-to-line fault. This testbed will be used to help develop closed-form expressions. Once fault currents are characterized and closed-form expressions are made, adequate protection systems can be designed. finally, this paper will include the simulation and experimental results of line-to-line fault characterization with a DC smoothing capacitor, and intermittent faults of various times.
BS, Electrical and Electronics Engineering, Shahroud University of Technology, 2009
Lead Service and Design Engineer
GE Healthcare
Willy Sedano
MS Graduate, 2018
Azadeh Mazaheri
MS Graduate
Research Focus: ENERGY EFFICIENCY AND MODELING ENERGY STORAGE FOR BUILDINGS
Abstract: An advanced Energy Storage device modeling, namely, Zinc Bromide, is proposed to integrate a new software Smartbuilds, developed by Marquette University, based on an integrated building. Smartbuilds will provide the platform to integrate all the components of the proposed Building which incorporate with renewable energy and energy storage system. The zinc bromide modeling results show that the battery’s open-circuit voltage is a direct function of the state of charge (SOC) of the battery. Furthermore, resistance is also a function of sate of charge at constant temperature. A Coulomb Counting technique is used to adjust the estimated SOC according to battery current. Simulation studies are made with Matlab/Simulink. Proposed Zinc bromide battery model has been compared with Energyplus, building energy simulation program, battery model and it has been translated to Energyplus battery model to integrate in Energyplus. Example case studies are provided to show the results.
MSEE from University of Wisconsin-Milwaukee, Milwaukee, WI, 2015
BS from Islamic Azad University of Najafabad, Najafabad, Iran 2003.
Swachala Veerapaneni
MS Graduate, May 2018
Thesis: ANALYSIS OF IMPACTS OF ELECTRICAL ARCHITECTURES, SOCIAL-ECONOMIC CONSIDERATIONS AND REGIONS, ON REQUIREMENTS FOR RESIDENTIAL COMBINED SOLAR AND BATTERY IMPLEMENTATIONS
Abstract: A community DC MG in an urban environment is analyzed and aimed at driving down the utility costs in a low-income household. A typical home conventional AC loads is compared with smart technologies to prove that utility bills can be significantly reduced. The optimal installation and usage of solar and battery energy storage is determined for the entire integrated community aiming to achieve net zero energy community.
This study revealed a need for better understanding of the loads in each house and load patterns across a wide range of regions nationally and more typical houses, as opposed to the specialized study of the Milwaukee DC microgrid. As a result, current
research also incorporates analysis of different architectures, for the Residential Microgrid modeling, for different types of homes in five different locations to contemplate theoretical and statistical understanding of suitable architecture. Critical AC loads are identified, and came up with an equivalent replacement for the DC Loads. Loads which are continually in use are taken into consideration, such as DC LED lights, Electronic Loads, Air Conditioner’s/Heat Pumps.So, proposed methods and systems cost less for an average home owner, than the one proposed by NREL Study for Installed Cost Benchmarks for Residential Solar Photovoltaics with Energy
Storage.
BSEE Jawaharlal Nehru Technological University, Hyderabad 2013
Md Abdul Gaffar
MS Graduate, May 2018
Thesis: DESIGN OF A HIGH FREQUENCY FOUR PORT TRANSFORMER FOR DC/DC CONVERTERS.
Abstract: Large scale integration of renewable energy systems (RES) and energy storage systems (ESS) demands a better connectivity between distributed sources and loads. Multi-port solid state transformer (MPSST) plays a critical role as a joint node to integrate RESs, ESSs, utility grid, and loads. MPSST offers several advantages including independent power flow control on each port, voltage or current regulations, compactness and portability, and galvanic isolation.
A co-simulation between the magnetic environment in Ansys Maxwell, and power electronics and control part in Ansys Simplorer, has been carried out to benefit from the utilization of the developed realistic high frequency transformer for the operation of the MPSST.
BSEE Bangladesh University of Engineering and Technology,2008
Kavya Shree Kuman
MS Graduate, 2017
Thesis: MANUAL FOR AUTOMATION OF Dc-MICROGRID COMPONENT USING MATLAB/SIMULINK AND FPGAS
Abstract: Solar Energy is one of the abundantly available renewable energy source. Solar panels are semiconductor materials which capture the solar energy from every band in the visible light spectrum, infrared spectrum and ultra violet spectrum and converts it into electrical energy.
The DC community microgrid is used to supplement utility electrical power supplied to the neighbored with renewable sources such as solar panels, emergency back-up power through batteries or generators. Smart Cloud Interconnected environment increases the standard of living and facilitates ease to rectify faults, debug components and reinstate or replace obsolete components with newer ones.
Automation of the DC microgrid components provides a simple yet efficient way to connect to the grid and to every component in the grid remotely. It is essential to find the node of failure in the grid for technicians and engineers to work on and to debug the issue to facilitate smooth running of the grid without shutdown. FPGAs are used as target devices for end synthesis of the model that is created on Simulink. These FPGAs are links between cloud and power electronics components. To utilize the energy resource efficiently we need to monitor the input and output of every component at every node in the grid. Simulating models on Simulink will let us connect the component and test engineer to the grid to detect any flaws or failures on time. FPGAs are easily reprogrammable and have long life with excellent capability to withstand stress.
This thesis report provides a set of procedures to create and simulate a real time component model and to generate HDL files to build a clean code which can be redeployed on target FPGAs.
BS, Electrical, Electronics and Communications Engineering, Visvesvaraya Technological University, 2015
Freelance Consultant, Pre-Startup Bengaluru
Mengyuan Qi
MS Graduate, 2017
Thesis: FAULT DISCRIMINATION USING SiC JFET BASED SELF-POWERED SOLID STATE CIRCUIT BREAKERS IN A RESIDENTIAL DC COMMUNITY MICROGRID
Abstract: This thesis validates the use of ultra-fast normally-on SiC JFET based self-powered solid state circuit breakers (SSCBs) as the main protective device for a 340Vdc residential DC community microgrid. These SSCBs will be incorporated into a radial distribution system so that line to line short circuit faults and other types of faults can be isolated anywhere within the microgrid.
Because of the nature and characteristics of short circuit fault inception in DC microgrids, the time-current trip characteristics of protective devices must be several orders of magnitude of faster than conventional circuit breakers. The proposed SSCB detects short circuit faults by sensing its drain-source voltage rise, and draws power from the fault condition to turn and hold off the SiC JFET. The new two-terminal SSCB can be directly placed in a circuit branch without requiring any external power supply or additional wiring.
To achieve the coordination between upstream and downstream SSCBs in the DC community microgrid, a little change has been made to the proposed SSCB. A resistor in the schematic of SSCB has been changed to a potentiometer to have a different response time to short circuit fault. In order to figure out the value of that potentiometer to get the best coordination, a transfer function is derived.
LTspice VI and PLECS are used to verify the analytical work in the design. In the simulation layout, the DC community microgrid has been simplified to a radial system and 5 SSCBs are connected in series. Short circuit fault is applied at different locations in the DC system to test the effectiveness of the coordination scheme.
MS, electrical and Power Transmission Installation, Installer, General, Chongqing University, 2018
BA Sc Electrical and Electronics Engineering, Yanshan University, 2015
Yihui Zhang
MS Graduate, 2017
Thesis: DEVICES SELECTION AND TOPOLOGY COMPARISON FOR MEDIUM VOLTAGE DC SOLID STATE CIRCUIT BREAKERS
Abstract: DC grid has been treated as a viable solution to solve green-house effect and reduce the cost of fossil fuels. Compared with AC grid, DC grid shows many inherent advantages, such as high efficiency power delivery, less expensive to deploy and no need for phase and frequency synchronization. However, over current protection for DC grid require fast response. To solve this problem, solid state DC circuit breakers need to be promoted.
In this thesis, thermal property was taken into consideration to find the most suitable semiconductor devices. Per unitized thermal resistance of the heat sink to the ambient was used to find the reasonable conducting current. Module MOV topology and one MOV topology were compared to see the voltage and current stress
ANSYS Simplorer is used to assist in the process. Simulation is used to see the waveform of the current stress and the voltage stress under ideal and non-ideal condition. According to the results, during the ideal condition the current stress and the voltage stress are almost the same. However, under the non-ideal condition, the current stress and voltage stress are different, and the module MOV mode topology is much more reliable and has less current and voltage stress.
Junyang Yu
MS Graduate, 2017
Thesis: GROUND FAULT LOCATION OF CABLE USING WAVELET IN DC MICROGRID
Abstract: As the proliferations of distributed generation and power electronic equipment in power systems, more and more researchers put focus on the DC microgrid. This study is based on cables in DC community microgrid. Single ground fault is considered in the cables connected hub garage and participating garages. With long length compared to other cables in the system, it is necessary to study the method to locate the ground fault when the fault happen in the buried cables.
Two approaches are studied. The traveling wave method is applied for analysis of transient process when the fault happens while the stable parameter analysis method used for the stable process after the fault already happened.
The cable model is defined using precise distributed element concept and packaged as a PLECS model. The simulation is based on the DC microgrid model in the Simulink environment with PLECS blocks.
The wavelet packet decomposition is applied in the processing of signal processing procedure. The wavelet packet helps to extract the key signal and eliminate the interference in both methods respectively. The results are analyzed to show the effectiveness of location methods and wavelet packet.
Qianqian Jiao
MS Graduate, 2017
Thesis: PLUG-IN GRID COMPATIBLE NEXT GENERATION POWER CONVERTERS
Abstract: The utilization of the DC low voltage distribution opens new possibilities for network development. Community DC microgrid is considered as an efficient solution for providing clean energy for residential areas. The connection of the DC microgrid to the AC utility grid would need a power electronic based rectifier. Voltage Source Rectifier (VSR) and Current Source Rectifier (CSR) are considered as the two options for such application. This study compares the two topologies based on their power density and efficiency. Silicon Carbide (SiC) switches are used for designing the rectifiers to get better power density and efficiency. The proximity of the rectifier to the residential area requires electromagnetic compatibility (EMC) of the rectifier with established standards such as IEC 61000-3-4 and FCC B. This analysis shows that CSR has higher efficiency and higher power density compared to VSR.
MS, Physics, University of Nebraska-Lincoln
Research Scientist/Electrical Engineer–Principal Investigator
National Energy Technology Laboratory
Sean Cunningham
MS Graduate, May 2017
Thesis: THEORY, SIMULATION, AND IMPLEMENTATION OF GRID CONNECTED BACK TO BACK CONVERTERS UTILIZING VOLTAGE ORIENTED CONTROL
Abstract: This work presents a back to back converter topology with the ability to connect two power systems of different voltages and frequencies for the exchange of power. By utilizing indirect AC/AC conversion decoupling is achieved between the power systems with one of the three-phase, two-level voltage source converters performing the AC/DC conversion that maintains the required DC bus voltage level at unity power factor while the other converter operates in all four quadrants supplying/consuming active and/or reactive power with the other power system. The prototype implementation resides at UW-Milwaukee’s USR Building microgrid test bed facility with an emphasis in the design to approach the requirements for harmonic control as recommended by IEEE 519-2014 without power filtering AC capacitors. The challenge in this project was to develop the model based firmware and control for the custom digital signal controller boards interfaced to Rockwell Automation’s PowerFlex 753-Series converters with only a high level knowledge of the proprietary power structure available.
BSEE from University of Minnesota-Twin Cities, 2004.
Ruijing Yang
MS Graduate, 2016
Thesis: THE STUDY OF LOCATING GROUND FAULTS IN DC MICROGRID USING WAVELET TRANSFORM
Abstract: As the proliferations of distributed generation and power electronic equipment in power systems, direct current (DC) microgrid emerged and attracted more and more researchers’ attentions. Protection of DC microgrid is a big challenge and to build a well-function protection system, locating the faults accurately is a critical issue. It is easy to find the location of short circuit faults in DC microgrid. However, it is difficult to locate ground faults in DC microgrid because of the spray capacitors and the large amount of distributed resources.
In this thesis, Wavelet Transform is applied to decompose the common mode currents that is collected at different sensor points in a DC microgrid and capture the characterization of every single ground fault. And based on these characterizations, a single ground fault location algorithm is proposed.
MATLAB/Simulink and PLECS are used to assist in the process. Simulink is used to build the three phase source feeding the DC microgrid and PLECS is used to build the model of DC microgrid and measure the common mode current at different sensor points when a single ground fault is applied.
Vikas Singh
MS Graduate, 2016
Thesis: SOLID STATE PROTECTIVE DEVICE TOPOLOGICAL TRADE-OFFS FOR MVDC SYSTEMS
Abstract: Presently accepted approaches to protection are “Unit-Based” which means the power converter(s) feeding the bus coordinate with no-load electromechanical switches to isolate faulted portions of the bus. However, “Breaker-Based” approaches, which rely upon solid state circuit breakers for fault mitigation can result in higher reliability of power and potentially higher survivability. The inherent speed of operation of solid state protective devices will also play a role in fault isolation, hence reducing stress level on all system components. A comparison study is performed of protective device topologies that are suitable for shipboard distribution systems rated between 4kVdc and 20kVdc from the perspectives of size and number of passive components required to manage the commutation energy during sudden fault events and packaging scalability to higher current and voltage systems. The implementation assumes a multi-chip Silicon Carbide 10kV, 240A MOSFET/JBS diode module. A static fault simulator device is proposed to characterize DC faults.
B. Tech, Electrical Engineering, Uttar Pradesh Technical University, 2011
Electrical Engineer
Danfoss Drives
Wei Fu
MS Graduate, 2019
Thesis: DESIGN AND COMPARISON OF Si-BASED AND SiC-BASED THREE-PHASE PV INVERTERS
Abstract: The opportunities for both power density and efficiency improvements of photovoltaic (PV) inverter have come with the development of commercially available wide bandgap (WBG) devices such as Gallium Nitride (GaN), and Silicon Carbide (SiC).
In this thesis, how the replacement of Silicon (Si) Insulated Gate Bipolar Transistor (IGBT), with SiC Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) affects the power density and efficiency of a solar inverter implementation is presented. The focus is on achieving a minimum volume of the output filter which meet the current harmonic performance of IEEE standard, while meeting the thermal constraint of the semiconductor device. Efficiency improvements are also characterized through an accurate calculation of device and magnetic component losses—the largest contributors to loss in the system.
MATLAB/Simulnk and PLECS are used to assist in the process. Simulation is used to calculate the differential mode pulsed voltages so that the required attenuation of the filter can be determined and to determine the maximum switching frequency at which the device can operate for a given heatsink design. Thus the power density can be compared. At the same time, by using the same filter but changing out devices, the efficiencies at the same power density can be compared.
According to the results, when both use the maximum junction temperature as the constraint, SiC-based inverter can operate at a much higher switching frequency, which leads to a significant decrease in filter components and resulting a higher power density than Si-based inverter. When operating at the same switching frequency, which means keeping the power density the same, SiC devices leads to an improvement in efficiency.
Yi Wang
MS Graduate, August 2014
Thesis: COUPLED ELECTROMAGNETIC AND THERMAL ANALYSIS AND DESIGN OPTIMIZATION OF SYNCHRONOUS ELECTRIC MACHINES
Abstract: A new technique for coupling the electromagnetic, thermal, and air-flow analysis is proposed for electronically controlled synchronous machines. A computationally efficient finite element analysis (CE-FEA) technique is employed for the electromagnetic field analysis. An equivalent circuit network is used for thermal and air-flow analysis. An iterative algorithm, which exploits the fact that the type of machines studied have very low rotor losses and also a relatively reduced dependency of core losses with temperature and load, has been developed. The overall computational time is significantly reduced in comparison with the conventional coupling method, such that the new technique is highly suitable for large scale optimization studies. An automated design optimization method based on differential evolution algorithms has also been developed and implemented on a multi-core computer system. Example case studies are provided for permanent magnet and for synchronous reluctance machines. Computational and experimental results from prototype motors are included.
BSEE from Changchun University of Technology,
China, 2012
Project Service Engineer
AvePoint in Changchun, China
Sidharth Ashok
MS Graduate, May 2014
Thesis: MODELING AND PROTECTION SCHEME FOR IEEE 34 RADIAL DISTRIBUTION FEEDER WITH AND WITHOUT DISTRIBUTED GENERATION
Abstract: The existing power system was not designed with distribution generation (DG) in mind. As DG penetration is being considered by many distribution utilities, there is a rising need to address many incompatibility issues which puts a big emphasis on the need to review and implement suitable protection scheme. The usual practice for existing distribution feeders is the Overcurrent scheme which includes coordination between fuses and reclosers. But when DG is added to the distribution feeder, the configuration is no more radial as there is contribution of fault currents from the DG’s and if the existing protection scheme is applied then this could lead to various issues like fuse misoperation or nuisance tripping considering temporary and permanent fault conditions.
This thesis presents a study on the modeling of existing IEEE 34 radial distribution feeder and scaling of the system from 24.9kV to 12.47kV keeping in mind the existing conditions and also proposes a protection scheme with and without the addition of DG’s to the feeder nodes. The protection scheme involves providing appropriate relaying with suitable fuse selection and Current transformer settings. Considerations for proper transformer grounding and capacitor bank fusing protection is also simulated and reviewed. When DG’s added, the results show increase in fault contribution and hence causing misoperations which needs to avoided. Relaying considerations are also provided when an islanded mode occurs. The entire analysis has been simulated by a combination of various tools like Aspen One liner, CYMDist and Wavewin with occasional simulations and calculations performed in MATLAB environment.
BS EEE, SASTRA University, India, 2012
Senior Engineer
Controls & Protection Engineering at National Grid
Ali Yousef
MS Graduate, June 2011
Thesis: WIND TURBINE ENERGY STORAGE LEVEL FOR LOW VOLTAGE RIDE THROUGH (LVRT)
Abstract: Renewable energy is a green source of energy that is clean, available and sustainable. Wind energy generation has been experiencing the largest growth among renewable sources due to lower cost and advanced technologies. Wind energy power plants or farms need low maintenance and last for long time. The increasing higher penetration of wind energy in the grid has transformed wind energy into major player in grid operation and economics. Wind energy systems now have to participate in grid support and provide ancillary services.
Variable wind speed leads to variable wind power generation, voltage fluctuations, and frequency deviations, which are the main problems related to wind energy integration into grid. These problems become more evident in weak grids. In addition, wind farms have to take the grid problems into consideration and have to provide support during grid instability and transients.
In this thesis, a PMSG wind turbine full energy conversion system design and modeling have been performed using Matlab Simulink. The system is a grid integrated and applies MPPT control to extract the maximum power from the wind and utilizes a full conversion circuitry to interface the unregulated generator AC power to the grid. Modules of Lithium-Ion Capacitors (LIC) have been placed on the DC bus in order to support the grid with wind energy power smoothing and LVRT. LICs offer high power density and reasonable energy density. During grid faults, wind energy can be stored in the LICs and discharged into grid as soon as the voltage restored. This feature will support the grid to stabilize the voltage. Detailed modeling of the architecture and controls have been performed to verify the viability of the proposed system.
BSEE from Birzait University, Palestine, 2009
Milad Pashapour
MS Graduate, June 2011
Thesis: DESIGN AND IMPLEMENTATION OF A SOLAR POWERED ELECTRIC GOLF CART
Abstract: With the rapidly growing energy demand and shrinking supply of expendable resources, recently, much attention has been paid to alternative energy sources and more efficient ways of harnessing energy. The Photovoltaic (PV) solar cells can directly convert sunlight to electricity. In this research work, design, simulation, and implementation for utilization ofsolar PV panels to power a golf cart have been performed. Three PV panels are installed on top of a golf cart and are designed to charge a 36 volt battery system. The maximum power rating of the three panels is 261 watts. This rating is the power output under Standard Test Conditions known as STC. We have also desined and utilized a Maximum Power Point Tracking (MPPT) intelligent controller which is able to vary the voltage of the panel to keep its operating point closer to its maximum output power at different sun irridations.
The actual power gain over a non-MPPT controller with the same panel will vary with conditions, but a 10-30% gain is typical. We are applying a multi-stage charging technique that allows for a fuller battery charge without reducing the battery life or “boiling off” the electrolyte. The battery is held at a higher voltage for a period of time while it gets the full charge, and then the voltage is reduced to provide maintenance charge without overcharging the battery. Temperature compensation avoids excessive electrolyte usage and thermal runaway at higher temperatures and helps compensate for increased internal resistance in the battery at lower temperatures. This results in a longer battery life due to not overcharging at higher temperatures while still preserving full charges at low temperatures.
The proposed system has been designed, modeled, implemented and tested. The results are presented and discussed in this thesis. The test results indicate that the installed PV panels can provide enough power for modest usage of the cart.
MSEE University of Tarbiat Modaress, Tehran, Iran, 2005
BSEE University of Polytechnic, Tehran, Iran, 2002
Electrical Engineer
Miller
Salaheddin Zabalawi
MS Graduate, December 2008
Thesis: A LINEAR GENERATOR FOR POWERING IMPLANTED ELECTRONIC DEVICES
Abstract: Due to recent developments in power electronics devices and systems, permanent magnet machines are finding many applications in various fields, including automotive systems and renewable energy. These machines provide high efficiency, compact size, robustness, light weight, and low noise. These features qualify them as the best suitable machine for medical applications. The system proposed is a self-contained, small size, and reliable device that can continuously provide power. The proposed linear generator will have two layers of Permanent Magnets (PM) and one layer of coils. It generates power from multidirectional movement. The movement of the device will cause the middle coils layer to move. The relative movement of the coils versus PMs, on two sides, creates a varying flux in the windings. This change in flux produces voltage in the winding and can be converted into electrical power if a load is connected. In order to provide a continuous power source, the muscle used in this system must not stop working. The best option for such a system is to use a muscle that is linked to the respiratory system. Some of these muscles are accessible without having to tap into the windpipes themselves. There are many potential locations in the human body for implantation of the proposed device. The primary target location is the abdominal wall, due to continuous movement, sufficient travel distance and small surgical risks. The output voltage produced by the generator is a very small, alternating-current (AC) waveform, which must be appropriately transformed and rectified for a given load.
BSEE from American University of Sharjah, United Arab Emirates, 2006.
Working for Honeywell Process Solutions, Abu Dhabi, U.A.E.
salaheddin.zabalawi@honeywell.com;
Thomas Laubenstein
MS Graduate, May 2010
Thesis: SPEED AND TORQUE CONTROL OF PERMANENT MAGNET SYNCHRONOUS GENERATORS FOR WIND POWER APPLICATIONS
Abstract: The world is constantly increasing its need for electrical power. Electronic devices are gaining greater popularity throughout the world. Studies show that power consumption will increase over 40% in the next 20 years. As a result new technologies are being investigated to help supply the need for the increased electrical power.
Energy resources are separated into two major groups: Non-Renewable and Renewable. Power production from non-renewable resources has been around for many, many, decades. The most widely used source of non-renewable resources is the coal-fired power plant. Even though coal has been well established it does have some undesired effects on the environment. It tends to add pollution, in the form of “greenhouse gasses”, to the environment and the supply is limited. The concept of producing power from renewable resources has regained popularity in recent years. Hydroelectric power plants have been used all over the world for many years. It is non-pollution and as long as water in the river keeps flowing the source for power will keep replenishing itself. Other forms of renewable energy power production are from wind, solar, and geothermal energy sources. Even though the renewable energy sources are considered to be non-polluting they do have some drawbacks. For example, power production is not always consistent and there are some undesirable impacts to the environment.
This thesis investigates one form of renewable energy power production. Wind energy has had an increasing amount of research to support it. This paper investigates maximum power production profile of a wind turbine containing a permanent magnet synchronous generator and implements both speed and torque controls during instances of higher wind speeds. Implementation is supported through simulation results.
BSEE from University of Wisconsin-Milwaukee, 1998.
Project Engineer
American Superconductor
Eric Biehr
MS Graduate, 2010
Thesis: X-RAY TUBE INDUCTION MOTOR DESIGN OPTIMIZATION TECHNIQUE
Abstract: High power CT X-ray tubes require the use of a rotating target to ensure the focal track is kept below the material’s temperature limit during x-ray generation. The target rotation is driven by a mono or poly-phase induction motor. Modern x-ray tubes vary in envelope size, bearing technology, moment of inertia, and have inherent motor design challenges such as large air gaps and wide temperature operating ranges leading to various motor sizes and performance requirements. An approach to design optimization utilizing Design Analysis of Computer Experiments with consideration for Design Analysis for Cost will be defined and demonstrated on a 3-phase induction motor for an x-ray tube. Multiple X’s (inputs) will be defined from envelope/size limitations, performance requirements, and standard induction motor design considerations. Four Y’s (outputs), including three performance requirements and one requirement to minimize cost, will be optimized through a total of 18,000 potential designs. This parameterized electro-mechanical design optimization achieves the simultaneous objectives of required performance in a small and lower cost package, achieving almost 50% estimated cost reduction.
This paper will present the approach and execution for an optimized induction motor design meeting all requirements, and practical application will be demonstrated experimentally on design prototypes with component level dynamometer bench tests, hence validating the software design tool.
BSEE University of Milwaukee-Wisconsin, 2004
Senior Development Engineer
GE Healthcare
Zoran Vrankovic
MS Graduate, 2006
Thesis Title: A NOVEL BATTERY CHARGER FOR AUTOMOTIVE APPLICATIONS
Abstract: In this thesis, a new power electronics topology is introduced for battery pulse charging. The topology is based on a bidirectional isolated Cuk converter. The charging method provides positive and negative current and resting periods. This charging method results in less generated heat and longer battery life cycle. Different operating modes of the system and its small signal analysis are presented. The small signal system has been modeled using MATLAB. Simulation results are also provided to validate the mathematical analysis.
BSEE from University of Wisconsin-Milwaukee, 2002.
Project Hardware Engineer
Rockwell Automation