PERFORMANCE ASSESS OF SELF-EXCITED IG DRIVEN BY WIND TURBINE WORKING WITH FC-TCR

This work presented a self-excited induction generator (SEIG) model controlled by an (FC-TCR) fixed capacitor-thyristor control reactor consisting of a large fixed capacitor in parallel with a thyristor controlled reactor in series with the constant inductance. Induction machines were used because they are capable of working at different speeds. The 3-phase IG was driven by the prime mover that represents the wind turbine. Also, constant voltage and frequency were obtained, regardless of the change in velocity, by using proportional integration (PI control) for each of them. This type of generator is used in isolated rural areas far from power transmission lines. The voltage and frequency are analyzed for each wind speed proposed in the model and calculating the required excitation amplitude and torque required to drive the induction generator. Therefore, it is now a key interest to develop an efficient, viable, economic, and controllable induction generator for harnessing energy from renewable sources. The strategy of control was implemented with MATLAB/Simulink

Challenges of Inductive Electric Vehicle Charging Systems in both Stationary and Dynamic Modes

Inductive power transfer as an emerging technology has become applicable in wide power ranges including Electric Vehicle, Electric Aircraft, wheelchair, cellphone, scooter and so on. Among them, inductive Electric Vehicle (EV) charging has gained great interest in the last decade due to many merits namely contactless technology, more convenience, full automotive charging process. However, inductive EV charging systems could bring about so many issues and concerns which are addressed in this dissertation. One of the critical challenges addressed in this dissertation is a virtual inertia based IPT controller to prevent the undesirable dynamics imposed by the EVs increasing number in the grid. Another adverse issue solved in this dissertation is detecting any metal object intrusions into the charging zone to the Inductive Power Transfer (IPT) systems before leading to heat generation on the metal or risk of fire. Moreover, in this dissertation, a new self-controlled multi-power level IPT controller is developed that enables EV charging level regulation in a wide range of power; suitable for different applications from golf-cart charging system (light duty EV) to truck (heavy duty EV). The proposed controller has many merits including easy to be implemented, cons-effective, and the least complexities compared to conventional PWM methods. Additionally, in this dissertation, the online estimation of IPT parameters using primary measurement including coupling factor, battery current and battery voltage is introduced; the developed method can find immediate applications for the development of adaptive controllers for static and dynamic inductive charging systems. Finally, the last objective of this research is physics-based design optimization techniques for the magnetic structures of inductive EV charging systems for dynamic application (getting charged while in motion). New configuration of IPT transmitting couplers with objective of high-power density, low power loss, low cost and less electromagnetic emission are designed and developed in the lab

Energy Shaping Control for Stabilization of Interconnected Voltage Source Converters in Weakly-Connected AC Microgrid Systems

With the ubiquitous installations of renewable energy resources such as solar and wind, for decentralized power applications across the United States, microgrids are being viewed as an avenue for achieving this goal. Various independent system operators and regional transmission operators such as Southwest Power Pool (SPP), Midcontinent System Operator (MISO), PJM Interconnection and Electric Reliability Council of Texas (ERCOT) manage the transmission and generation systems that host the distributed energy resources (DERs). Voltage source converters typically interconnect the DERs to the utility system and used in High voltage dc (HVDC) systems for transmitting power throughout the United States. A microgrid configuration is built at the 13.8kV 4.75MVA National Center for Reliable Energy Transmission (NCREPT) testing facility for performing grid-connected and islanded operation of interconnected voltage source converters. The interconnected voltage source converters consist of a variable voltage variable frequency (VVVF) drive, which powers a regenerative (REGEN) load bench acting as a distributed energy resource emulator. Due to the weak-grid interface in islanded mode testing, a voltage instability occurs on the VVVF dc link voltage causing the system to collapse. This dissertation presents a new stability theorem for stabilizing interconnected voltage source converters in microgrid systems with weak-grid interfaces. The new stability theorem is derived using the concepts of Dirac composition in Port-Hamiltonian systems, passivity in physical systems, eigenvalue analysis and robust analysis based on the edge theorem for parametric uncertainty. The novel stability theorem aims to prove that all members of the classes of voltage source converter-based microgrid systems can be stabilized using an energy-shaping control methodology. The proposed theorems and stability analysis justifies the development of the Modified Interconnection and Damping Assignment Passivity-Based Control (Modified IDA-PBC) method to be utilized in stabilizing the microgrid configuration at NCREPT for mitigating system instabilities. The system is simulated in MATLAB/SimulinkTM using the Simpower toolbox to observe the system’s performance of the designed controller in comparison to the decoupled proportional intergral controller. The simulation results verify that the Modified-IDA-PBC is a viable option for dc bus voltage control of interconnected voltage source converters in microgrid systems

Power quality improvement utilizing photovoltaic generation connected to a weak grid

Microgrid research and development in the past decades have been one of the most popular topics. Similarly, the photovoltaic generation has been surging among renewable generation in the past few years, thanks to the availability, affordability, technology maturity of the PV panels and the PV inverter in the general market. Unfortunately, quite often, the PV installations are connected to weak grids and may have been considered as the culprit of poor power quality affecting other loads in particular sensitive loads connected to the same point of common coupling (PCC). This paper is intended to demystify the renewable generation, and turns the negative perception into positive revelation of the superiority of PV generation to the power quality improvement in a microgrid system. The main objective of this work is to develop a control method for the PV inverter so that the power quality at the PCC will be improved under various disturbances. The method is to control the reactive current based on utilizing the grid current to counteract the negative impact of the disturbances. The proposed control method is verified in PSIM platform. Promising results have been obtaine

Integration of a High Speed Megawatt Class Induction Motor and High Frequency Variable Speed Drive System through Modeling and Simulation

With the prominence of high speed, MW class motor usage in various industries such as the petrochemical and natural gas sectors, advancements in related technologies allow for achievable benefits such as increased energy efficiency, compressed power density, and cost savings. A novel high frequency variable speed drive (VSD) and motor system is being developed by Clemson University and TECO-Westinghouse Motor Company through a Department of Energy (DOE) project. In order to test this prototype, a dynamometer setup is required, involving another induction motor, another motor drive, and a gearbox. The system is modeled and simulated through MATLAB/Simulink in order to predict system behavior, control propagation, and protection limits. Individual parts of the system are individually modeled and evaluated before integrating the entire system together in software. Simulation of the various components involve a plethora of parameters, settings, and topologies to be researched and analyzed. V/Hz is used as the control method for the motors involved in the system. Voltage sources are modeled to represent this method and output desired waveforms. Both speed and torque outputs on the machines are managed in specific manners to evaluate desired performance. Open loop and closed loop controls are explored and expressed through the results. An equation is given to relate the V/Hz setpoints of both high speed and low speed sides of the integrated system to conduct a full load test. Through these simulation efforts, actual system test procedures can be established and safety concerns can be assessed

Characterization and emulation of a new supercapacitor-type energy storage device

The work in this thesis focuses on the characterization, modeling and emulation of both the supercapacitor and the new supercapattery energy storage device. The characterization involves the selection of dynamic models and experimental methodologies to derive model parameters. The characterizing processes focus on predicting short-term device dynamics, energy retention (self-discharging) and losses and round-trip efficiency. A methodology involving a pulse current method is applied for the first time to identify a model parameter to give fast device dynamic characteristics and a new constant power cycling method is used for evaluating round-trip efficiency. Experimental results are shown for a number of supercapacitor and supercapattery devices and good results are obtained. The derived models from the characterization results are implemented into the emulator system and the emulator system is used to mimic the dynamic characteristics of a scaled-up 1kW supercapattery device. The thesis also addresses voltage equalizing circuits and reports a study that investigates efficiency, a cell voltage deviation and voltage equalizing time for different control methods

Power Quality Improvement of Distributed Generation Integrated Network with Unified Power Quality Conditioner.

With the increased penetration of small scale renewable energy sources in the electrical distribution network, maintenance or improvement of power quality has become more critical than ever where the level of voltage and current harmonics or disturbances can vary widely. For this reason, Custom Power Devices (CPDs) such as the Unified Power Quality Conditioner (UPQC) can be the most appropriate solution for enhancing the dynamic performance of the distribution network, where accurate prior knowledge may not be available. Therefore, the main objective of the present research is to investigate the (i) placement (ii) integration (iii) capacity enhancement and (iv) real time control of the Unified Power Quality Conditioner (UPQC) to improve the power quality (PQ) of a distributed generation (DG) network connected to the grid or microgrid