Engineering Commons^™

Optimal Combinations Of Utility Level Renewable Generators For A Net Zero Energy Microgrid Considering Different Utility Charge Rates, Evan S. Jones, Huangjie Gong, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

High initial investment and the intermittent nature of resources are major challenges for large scale renewable generation. The size of photovoltaic (PV) and wind turbine (WT) farms in the microgrid needs optimized to avoid curtailment and to efficiently meet the demand of a power system. Battery energy storage systems (BESSs) may also be used to improve flexibility. This paper explores the optimal sizing for PV and wind generators, as well as a BESS at the utility level for a large grid-connected net zero energy (NZE) hybrid microgrid considering characteristics such as initial investment, levelized cost of energy (LCOE), operating costs, …

Overview Of Flywheel Systems For Renewable Energy Storage With A Design Study For High-Speed Axial-Flux Permanent-Magnet Machines, Murat G. Kesgin, Peng Han, Narges Taran, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

Flywheel energy storage is considered in this paper for grid integration of renewable energy sources due to its inherent advantages of fast response, long cycle life and flexibility in providing ancillary services to the grid, such as frequency regulation, voltage support, etc. The fundamentals of the technology and recent developments are reviewed, firstly with an emphasis on the design considerations and performance metrics. Then the progress and development trends in electric motor/generators employed in flywheel energy storage systems (FESS) are summarized, showing the potential of axial-flux permanent-magnet (AFPM) machines in such applications. Design examples of high-speed AFPM machines are provided …

Smart Plug And Circuit Breaker Technologies For Residential Buildings In The Us, Rosemary E. Alden, Peng Han, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

A significant proportion of the total energy in conventional homes across the United States is used by electric plug loads, which include various electronic devices and home appliances, excluding the heating, ventilation and air conditioning (HVAC) units and electric water heaters. Considerable energy savings are expected to be possible by managing these plug loads effectively based on user behavior data. Smart plugs and circuit breakers that can control and monitor energy usage on a real-time basis are becoming increasingly popular alongside the rapid development of smart home energy management. This paper reviews the recent advances on the subject matter with …

Systematic Comparison Of Two Axial Flux Pm Machine Topologies: Yokeless And Segmented Armature Versus Single Sided, Narges Taran, Greg Heins, Vandana Rallabandi, Dean Patterson, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper systematically compares two axial flux permanent magnet (AFPM) machines designed for a university student racing car application: a double-rotor single-stator yokeless and segmented armature (YASA) structure, and a single- stator single-rotor configuration. Both machines are optimized for minimum loss and active weight using 3D finite element analysis and the highest performing candidate designs are compared in more detail. The studies indicate that the benefits offered by the YASA configuration over the single-stator single-rotor machine are achieved only for specific designs that are heavier. For the design space with lower mass, albeit with increased losses, the Pareto front designs …

On The Optimal Energy Controls For Large Scale Residential Communities Including Smart Homes, Huangjie Gong, Vandana Rallabandi, Michael L. Mcintyre, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

Residences with smart home energy management (HEM) systems and solar generation are modifying domestic load profiles. Moreover, the growing penetration of solar photovoltaic (PV) energy brings the total net power demand further down as houses become local generators. High PV penetration introduces technical challenges for the power system including the "duck curve". This paper proposes a co-simulation framework for high PV penetration smart energy communities which allows the simultaneous simulation of home energy consumption along with control algorithms for each house, as well as system power flow. Models are developed and presented for one of the largest rural field demonstrators …

Measurement And Estimation Of The Equivalent Circuit Parameters For Multi-Mw Battery Systems, Oluwaseun M. Akeyo, Vandana Rallabandi, Nicholas Jewell, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper proposes and validates through simulations and measurements, a procedure for the determining the equivalent circuit parameters of large utility-scale batteries. It is considered that a large battery includes multiple cells connected in series and parallel, and therefore, its equivalent circuit can be represented as a series-parallel network of state of charge (SOC) dependent resistors and capacitors. Tests for determining these equivalent circuit parameters are proposed. These tests involve subjecting the battery energy storage system (BESS) to multiple charge and discharge cycles, while monitoring the terminal voltage and current response. A method for post-processing and analyzing the measurements in …

Axial-Field Vernier-Type Flux Modulation Machines For Low-Speed Direct-Drive Applications, Vandana Rallabandi, Peng Han, Murat G. Kesgin, Narges Taran, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper proposes different configurations of axial-field machines featuring a very large ratio of the number of rotor poles to stator teeth and coils suitable for low-speed direct-drive traction applications. The machines have a single rotor with spoke-type permanent magnets and the stator teeth include auxiliary slots, the function of which is to enhance the high-polarity component of the stator magnetomotive force interacting with the rotor to produce a net torque. The machines can be constructed with three or two phases, in which case they inherently exhibit high tolerance to faults due to the combined effect of a lack of …

On The Control Of A Solid State Transformer For Multi-Mw Utility-Scale Pv-Battery Systems, Yibin Zhang, Oluwaseun M. Akeyo, Jiangbiao He, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

The utility-scale photovoltaic (PV)-battery systems typically include multiple power converters connected to the grid via traditional line frequency transformers (LFT), which may be considered bulky, and inefficient when compared with the emerging solid state transformers (SST). This paper proposes a SST with power and voltage controls for utility-scale PV-battery systems. The PV system was modeled based on available data from a universal solar facility located in Kentucky, USA. Furthermore, this paper provides detailed controller designs for the proposed utility-scale PV-battery system based on a SST which includes: the PV-side dual-active bridge (DAB) converter tracks the maximum power point, the PV …

A Hybrid Analytical And Fe-Based Method For Calculating Ac Eddy Current Winding Losses Taking 3d Effects Into Account, Narges Taran, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper proposes a new hybrid analytical and numerical FE-based method for calculating ac eddy current losses in wire windings and demonstrates its applicability for axial flux electric machines. The method takes into account 3D field effects in order to achieve accurate results and yet greatly reduce computational efforts. It is also shown that hybrid methods based on 2D FE models, which require semi-empirical correction factors, may over-estimate the eddy current losses. The new 3D FE-based method is advantageous as it employs minimum simplifications and considers the end turns in the eddy current path, the magnetic flux density variation along …

Modeling And Simulation Of A Utility-Scale Battery Energy Storage System, Oluwaseun M. Akeyo, Vandana Rallabandi, Nicholas Jewell, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper presents the modeling and simulation study of a utility-scale MW level Li-ion based battery energy storage system (BESS). A runtime equivalent circuit model, including the terminal voltage variation as a function of the state of charge and current, connected to a bidirectional power conversion system (PCS), was developed based on measurements from an operational utility-scale battery demonstrator. The accelerated response of the battery unit was verified by pulse discharging it from maximum to minimum SOC and its application for grid resiliency was demonstrated through an example droop control frequency response. For the purpose of validating the equivalent BESS …

Load Variation Reduction By Aggregation In A Community Of Rooftop Pv Residences, Huangjie Gong, Vandana Rallabandi, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper performs computational studies and develops control schemes for a virtual power plant (VPP) network formed by a community of homes with rooftop solar PV generation, and battery energy storage. Appropriate control and scheduling of the battery operations, and peer-peer power flow between the homes provide a possible solutions for reducing the higher costs and uncertainties brought to grid by high solar PV penetration. The residential community studied here includes twelve homes categorized into four types depending on whether they have energy storage or rooftop solar PV panels. The homes exchange power among themselves, and the real-time electricity rate …

Beneficial Reuse Of Industrial Co2 Emissions Using A Microalgae Photobioreactor: Waste Heat Utilization Assessment, Daniel T. Mohler, Michael H. Wilson, Zhen Fan, John G. Groppo, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

Microalgae are a potential means of recycling CO₂ from industrial point sources. With this in mind, a novel photobioreactor (PBR) was designed and deployed at a coal-fired power plant. To ascertain the feasibility of using waste heat from the power plant to heat algae cultures during cold periods, two heat transfer models were constructed to quantify PBR cooling times. The first, which was based on tabulated data, material properties and the physical orientation of the PBR tubes, yielded a range of heat transfer coefficients of 19–64 W m⁻² K⁻¹ for the PBR at wind speeds of 1–10 …

Waved: A Coreless Axial Flux Pm Motor For Drive Systems With Constant Power Operation, Narges Taran, Vandana Rallabandi, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

In this paper, a two-phase coreless AFPM machine with wave winding, 2-stators, and 3-rotors for traction applications is studied. A highly general optimization method, employing 3D FEA as the computational engine is employed. Number of poles in addition to other geometrical variables are included as independent optimization variables. A method for extending the speed range by rotating one of the stator discs with respect to the other at constant power operation is proposed. An inverter configuration including Si and wide band gap devices is proposed to be employed in conjunction with the machine under study. The study includes a comparison …

Modeling And Control Of A Multiport Converter Based Ev Charging Station With Pv And Battery, Yibin Zhang, Jiangbiao He, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

As an environmental friendly vehicle, the increasing number of electrical vehicles (EVs) leads to a pressing need of widely distributed charging stations, especially due to the limited on-board battery capacity. However, fast charging stations, especially super-fast charging stations may stress power grid with potential overload at peaking time, sudden power gap and voltage sag. This paper discusses the detailed modeling of a multiport converter based EV charging station integrated with PV power generation, and battery energy storage system, by using ANSYS TwinBuilder. In this paper, the control scheme and combination of PV power generation, EV charging station, and battery energy …

Electric Aircraft System Co-Simulation Including Body, Propeller, Propulsion, And Energy Storage Models, Damien Lawhorn, Vandana Rallabandi, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper discusses the multi physics modeling of an electric aircraft with distributed electric propulsion. Mathematical models for the aircraft body, propellers, propulsive motors, power electronics inverters, and batteries are developed. Two types of models are proposed for the power electronics inverters and electric machines, namely, average models which allow study of the aircraft performance under a specified mission profile, and detailed switching models used for transient examination. A new simulation framework was developed to allow communication between these two types of models so that losses and thermal stresses in the power electronics converters can be estimated especially during takeoff, …

Anonymous And Efficient Message Authentication Scheme For Smart Grid, Libing Wu, Jing Wang, Sherali Zeadally, Debiao He

Information Science Faculty Publications

Smart grid has emerged as the next-generation electricity grid with power flow optimization and high power quality. Smart grid technologies have attracted the attention of industry and academia in the last few years. However, the tradeoff between security and efficiency remains a challenge in the practical deployment of the smart grid. Most recently, Li et al. proposed a lightweight message authentication scheme with user anonymity and claimed that their scheme is provably secure. But we found that their scheme fails to achieve mutual authentication and mitigate some typical attacks (e.g., impersonation attack, denial of service attack) in the smart grid …

Inductance Testing For Ipm Synchronous Machines According To The New Ieee Std 1812 And Typical Laboratory Practices, Vandana Rallabandi, Narges Taran, Dan M. Ionel, Ping Zhou

Power and Energy Institute of Kentucky Faculty Publications

Equivalent circuit parameters serve as the basis for performance estimation and implementation of power electronic drives controls and therefore their accurate evaluation is very important. Specified in the newly approved IEEE Std 1812, a short-circuit test can be employed, in combination with an open-circuit measurement, in order to determine the back emf and the synchronous inductance. In the case of interior permanent magnet (IPM) machines, this approach can be used only to determine the d-axis inductance and additional and separate measurements are required for the q-axis inductance. In this respect, various methods, inclusive of dc step response tests, on-load tests, …

Design Optimization Of Electric Machines With 3d Fea And A New Hybrid Doe-De Numerical Algorithm, Narges Taran, Vandana Rallabandi, Dan M. Ionel, Greg Heins, Dean Patterson, Ping Zhou

Power and Energy Institute of Kentucky Faculty Publications

This paper discusses the multi-objective optimization of axial flux permanent magnet (AFPM) machines with ferrite spoke-type magnets, utilizing 3D finite element models. Three-dimensional finite element analysis is computationally expensive, and furthermore, substantial computation time is expended by optimization algorithms in evaluating low performing designs whose performance is far from the optimum if the search space is not specified correctly. In this regard, this work proposes two new methods for identifying the search space. The search is limited to ranges of input geometric variables where high performing designs are likely to be found. The optimization algorithm utilized is based on surrogate …

A Comparative Study Of Methods For Calculating Ac Winding Losses In Permanent Magnet Machines, Narges Taran, Vandana Rallabandi, Dan M. Ionel, Greg Heins, Dean Patterson

Power and Energy Institute of Kentucky Faculty Publications

In this study different methods of estimating the additional ac winding loss due to eddy currents at open-circuit are explored. A comparative study of 2D and 3D FEA, and hybrid numerical and analytical methods is performed in order to recommend feasible approaches to be employed. Axial flux permanent magnet (AFPM) machine case studies are included, namely a machine with open slots and a coreless configuration. These machine topologies are expected to present a substantial amount of ac winding loss, which would therefore need to be considered during optimal design. This study is one of the first ones to compare meticulous …

A Systematic Study On The Effects Of Dimensional And Materials Tolerances On Permanent Magnet Synchronous Machines Based On The Ieee Std 1812, Narges Taran, Vandana Rallabandi, Dan M. Ionel, Ping Zhou, Mark Theile, Greg Heins

Power and Energy Institute of Kentucky Faculty Publications

In the process of designing and manufacturing an electrical machine, a systematic study of dimensional and material tolerances is of the utmost importance. This paper proposes a systematic method by which the effect of design specification variations on permanent magnet (PM) synchronous machine performance may be identified and quantified. The method combines design of experiments techniques, open-circuit and short-circuit physical measurements, and virtual test simulations conducted based on the recently approved IEEE Std 1812 testing guide. Three case studies, two provided by a spoke-type PM radial field machine configuration, in two designs with different electromagnetic loading, and an axial flux …

Estimation Of Transmission Line Parameters Using Linear Method With Synchronized And Unsynchronized Data, Mustafa Lahmar

Theses and Dissertations--Electrical and Computer Engineering

Accurate value of transmission line parameters is important for power system protection applications, especially for distance relays whose zone settings are based on positive sequence line impedance. The research is devoted to estimating transmission line positive-sequence parameters from synchronized or unsynchronized measurements of voltage and current phasors that are obtained at both terminals of the line. The positive sequence parameters including series impedance and shunt admittance can be linearly estimated. The linear least square algorithm has been derived in this dissertation for different transmission line configurations. The algorithm is able to handle both synchronized and unsynchronized measurements and deal with …

Fault Location Techniques Using The Traveling Wave Method And The Discrete Wavelet Transform, Wesley Fluty

Theses and Dissertations--Electrical and Computer Engineering

Fault location within electric power systems is an important topic that helps reduce outage duration and increases reliability of the system. This paper explores the topic of fault location using traveling waves generated by fault conditions and the discrete wavelet transform used for time-frequency analysis. The single-ended and double-ended traveling wave methods are presented and evaluated on a single circuit and double circuit 500kV system modeled using MATLAB SIMULINK. Results are compared on the basis of wavelet used for analysis, sampling rate, and fault resistance.

Incorporating Battery Energy Storage Systems Into Multi-Mw Grid Connected Pv Systems, Vandana Rallabandi, Oluwaseun M. Akeyo, Nicholas Jewell, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper analyzes the configuration, design, and operation of multi-MW grid connected solar photovoltaic (PV) systems with practical test cases provided by a 10-MW field development. In order to improve the capacity factor, the PV system operates at its maximum power point during periods of lower irradiance, and the power output is limited to a rated value at high irradiance. The proposed configuration also incorporates a utility scale battery energy storage system (BESS) connected to the grid through an independent inverter and benefits of the experience gained with a 1-MW 2-MWh BESS large demonstrator. The BESS power smoothing and frequency …

Optimal Distribution Feeder Reconfiguration With Distributed Generation Using Intelligent Techniques, Ahmad Ghaweta

Theses and Dissertations--Electrical and Computer Engineering

Feeder reconfiguration is performed by changing the open/close status of two types of switches: normally open tie switches and normally closed sectionalizing switches. A whole feeder or part of a feeder may be served from another feeder by closing a tie switch linking the two while an appropriate sectionalizing switch must be opened to maintain the radial structure of the system. Feeder reconfiguration is mainly aiming to reduce the system overall power losses and improve voltage profile. In this dissertation, several approaches have been proposed to reconfigure the radial distribution networks including the potential impact of integrating Distributed Energy Resources …

Optimum Design Of Axial Flux Pm Machines Based On Electromagnetic 3d Fea, Narges Taran

Theses and Dissertations--Electrical and Computer Engineering

Axial flux permanent magnet (AFPM) machines have recently attracted significant attention due to several reasons, such as their specific form factor, potentially higher torque density and lower losses, feasibility of increasing the number of poles, and facilitating innovative machine structures for emerging applications. One such machine design, which has promising, high efficiency particularly at higher speeds, is of the coreless AFPM type and has been studied in the dissertation together with more conventional AFPM topologies that employ a ferromagnetic core.

A challenge in designing coreless AFPM machines is estimating the eddy current losses. This work proposes a new hybrid analytical …

Mathematical Programming Approach For The Design Of Satellite Power Systems, Allen Flath Iii

Theses and Dissertations--Electrical and Computer Engineering

Satellite power systems can be understood as islanded dc microgrids supplied by specialized and coordinated solar cell arrays augmented by electrochemical battery systems to handle high-power loads and periods of eclipse. The periodic availability of power, the limited capacity of batteries, and the dependence of all mission service on power consumption create a unique situation in which temporal power and energy scarcity exist. A multi-period model of an orbital satellite power system’s performance over a mission’s duration can be constructed. A modular power system architecture is used to characterize the system’s constraints. Using mathematical programming, an optimization problem can be …

Curricular Optimization: Solving For The Optimal Student Success Pathway, William G. Thompson-Arjona

Theses and Dissertations--Electrical and Computer Engineering

Considering the significant investment of higher education made by students and their families, graduating in a timely manner is of the utmost importance. Delay attributed to drop out or the retaking of a course adds cost and negatively affects a student’s academic progression. Considering this, it becomes paramount for institutions to focus on student success in relation to term scheduling.

Often overlooked, complexity of a course schedule may be one of the most important factors in whether or not a student successfully completes his or her degree. More often than not students entering an institution as a first time full …

Advanced Fault Area Identification And Fault Location For Transmission And Distribution Systems, Wen Fan

Theses and Dissertations--Electrical and Computer Engineering

Fault location reveals the exact information needed for utility crews to timely and promptly perform maintenance and system restoration. Therefore, accurate fault location is a key function in reducing outage time and enhancing power system reliability.

Modern power systems are witnessing a trend of integrating more distributed generations (DG) into the grid. DG power outputs may be intermittent and can no longer be treated as constants in fault location method development. DG modeling is also difficult for fault location purpose. Moreover, most existing fault location methods are not applicable to simultaneous faults. To solve the challenges, this dissertation proposes three …

Study Of Factors Affecting Distribution System Pv Hosting Capacity, Fanxun Li

Theses and Dissertations--Electrical and Computer Engineering

As renewable energy plays an increasingly important role in the power system, the addition of PV systems to the distribution network has become a major trend in the current power system development. However, if a PV system with excessive capacity is added to the distribution network, voltage problems may occur in the system. Hence, it is important to determine the capacity of the PV system that can be added at the distribution system.

The thesis aims to identify the major factors that affect the PV hosting capacity of distribution systems. The thesis studies various scenarios for the IEEE-123 test network …