A Hybrid Method of Performing Electric Power System Fault Ride-Through Evaluations on Medium Voltage Multi-Megawatt Devices

This dissertation explores the design and analysis of a Hybrid Method of performing electrical power system fault ride-through evaluations on multi-megawatt, medium voltage power conversion equipment. Fault ride-through evaluations on such equipment are needed in order to verify and validate full scale designs prior to being implemented in the field. Ultimately, these evaluations will help in reducing the deployment risks associated with bringing new technologies into the marketplace. This is especially true for renewable energy and utility scale energy storage systems, where a significant amount of attention in recent years has focused on their ever increasing role in power system security and stability. The Hybrid Method couples two existing technologies together - a reactive voltage divider network and a power electronic variable voltage source - in order to overcome the inherent limitation of both methods, namely the short circuit duty required for implementation. This work provides the background of this limitation with respect to the existing technologies and demonstrates that the Hybrid Method can minimize the fault duty required for fault evaluations. The physical system, control objectives, and operation cycle of the Hybrid Method are analyzed with respect to the overall objective of reducing the fault duty of the system. A vector controller is designed to incorporate the time variant nature of the Hybrid Method operation cycle, limit the fault current seen by the power electronic variable voltage source, and provide regulation of the voltage at the point of common coupling with the device being evaluated. In order to verify the operation of both the Hybrid Method physical system and vector controller, a controller hardware-in-the-loop experiment is created in order to simulate the physical system in real-time against the prototype implementation of the vector controller. The physical system is simulated in a Real Time Digital Simulator and is controlled with the Hybrid Method vector controller implemented on a National Instruments FPGA. In order to evaluate the complete performance of the Hybrid Method, both a synchronous generator and a doubly-fed induction generator are modeled as the device under test in the simulations of the physical system. Finally, the results of the controller hardware-in-the-loop experiments are presented which demonstrate that the Hybrid Method is a viable solution to performing fault ride-through evaluations on multi-megawatt, medium voltage power conversion equipment

Grid and rotor sides of doubly-fed induction generator-based wind energy conversion system using sliding mode control approach

ix, 78 leaves : illustrations (chiefly coloured) ; 29 cmIncludes abstract and appendix.Includes bibliographical references (leaves 65-78).This thesis deals with the analysis, modeling, and control of a Doubly-Fed Induction machine used as a wind turbine generator. A sliding mode control scheme is applied to control the power and Dc-link voltage. Two back-to-back converters are used at rotor and stator sides. At the rotor side, power control is achieved by controlling the rotor current, while at the grid side, an active power transfer is used to model the dc-link voltage. Overall robustness and tracking performance are enhanced to deal with uncertainties due to the structure of the sliding mode control law, compensation combinations, sliding and integral terms. An experimental 2-kw DFIG wind turbine system was used to validate the proposed control system. Based on the results obtained, the proposed system showed good capabilities in tracking and control under various operating conditions as well as robustness to uncertainties

Modeling of doubly-fed induction generators connected to distribution system based on eMEGASim® real-time digital simulator

This study is aimed to model and develop a stable test bed for a wind farm composed of six doubly-fed induction generators (DFIGs) connected to a distribution system based on the OPAL-RT’s eMEGASim® real-time digital simulator. The system in this research consists of a 9 MW wind farm, an average SimpowerSystems® DFIG wind turbine, connected to a 13.8 kV IEEE 14 bus distribution network. A Simulink model was designed and built using SimPowerSystem Simulink of Matlab R2011a. Most of existing studies on the simulation relevant to wind power mainly focus on off-line simulation. Therefore, the model has been rebuilt on the RT-LAB environment based on the OPAL-RT’s eMEGASim® real-time digital simulator to test the wind farm performance at the same rate as actual time. After running the model on eMEGASim® real-time digital simulator, some studies such as three-phase to ground fault and voltage sag have been made to test the response of the model

Fault Diagnosis in Wind Power System Based on Intelligent Techniques

Wind energy is one of the most important sources as well as being environmentally friendly and sustainable. In this paper, different types of faults of Doubly-Fed Induction Generator (DFIG) have been studied based on Artificial Neural Network (ANN), Particle Swarm Optimization (PSO) and Field Programmable Gate Array. To simulate the wind generators model MATLAB/Simulink program has been used. Artificial Neural Network (ANN) is trained for detection the faults and (PSO) technique is used to get the best weights. After the training process, the network was transformed into a Simulink program and then converted into the Very High Speed Description Language (VHDL) for downloading on the (FPGA) card, which in turn is used to detect and diagnosis the presence of faults where it can be re-programmed with high response and accuracy

Overview of Real-Time Simulation as a Supporting Effort to Smart-Grid Attainment

abstract: The smart-grid approach undergoes many difficulties regarding the strategy that will enable its actual implementation. In this paper, an overview of real-time simulation technologies and their applicability to the smart-grid approach are presented as enabling steps toward the smart-grid’s actual implementation. The objective of this work is to contribute with an introductory text for interested readers of real-time systems in the context of modern electric needs and trends. In addition, a comprehensive review of current applications of real-time simulation in electric systems is provided, together with the basis to understand real-time simulation and the topologies and hardware used to implement it. Furthermore, an overview of the evolution of real-time simulators in the industrial and academic background and its current challenges are introduced.The final version of this article, as published in Energies, can be viewed online at: http://www.mdpi.com/1996-1073/10/6/81

Induction Motors

AC motors play a major role in modern industrial applications. Squirrel-cage induction motors (SCIMs) are probably the most frequently used when compared to other AC motors because of their low cost, ruggedness, and low maintenance. The material presented in this book is organized into four sections, covering the applications and structural properties of induction motors (IMs), fault detection and diagnostics, control strategies, and the more recently developed topology based on the multiphase (more than three phases) induction motors. This material should be of specific interest to engineers and researchers who are engaged in the modeling, design, and implementation of control algorithms applied to induction motors and, more generally, to readers broadly interested in nonlinear control, health condition monitoring, and fault diagnosis

Comprehensive Review on Detection and Classification of Power Quality Disturbances in Utility Grid With Renewable Energy Penetration

The global concern with power quality is increasing due to the penetration of renewable energy (RE) sources to cater the energy demands and meet de-carbonization targets. Power quality (PQ) disturbances are found to be more predominant with RE penetration due to the variable outputs and interfacing converters. There is a need to recognize and mitigate PQ disturbances to supply clean power to the consumer. This article presents a critical review of techniques used for detection and classification PQ disturbances in the utility grid with renewable energy penetration. The broad perspective of this review paper is to provide various concepts utilized for extraction of the features to detect and classify the PQ disturbances even in the noisy environment. More than 220 research publications have been critically reviewed, classified and listed for quick reference of the engineers, scientists and academicians working in the power quality area

Power Converter of Electric Machines, Renewable Energy Systems, and Transportation

Power converters and electric machines represent essential components in all fields of electrical engineering. In fact, we are heading towards a future where energy will be more and more electrical: electrical vehicles, electrical motors, renewables, storage systems are now widespread. The ongoing energy transition poses new challenges for interfacing and integrating different power systems. The constraints of space, weight, reliability, performance, and autonomy for the electric system have increased the attention of scientific research in order to find more and more appropriate technological solutions. In this context, power converters and electric machines assume a key role in enabling higher performance of electrical power conversion. Consequently, the design and control of power converters and electric machines shall be developed accordingly to the requirements of the specific application, thus leading to more specialized solutions, with the aim of enhancing the reliability, fault tolerance, and flexibility of the next generation power systems

Lithium-Ion Ultracapacitor Energy Storage Integrated with a Variable Speed Wind Turbine for Improved Power Conversion Control

The energy of wind has been increasingly used for electric power generation worldwide due to its availability and ecologically sustainability. Utilization of wind energy in modern power systems creates many technical and economical challenges that need to be addressed for successful large scale wind energy integration. Variations in wind velocity result in variations of output power produced by wind turbines. Variable power output becomes a challenge as the amount of output power of the wind turbines integrated into power systems increases. Large power variations cause voltage and frequency deviations from nominal values that may lead to activation of relay protective equipment, which may result in disconnection of the wind turbines from the grid. Particularly community wind power systems, where only one or a few wind turbines supply loads through a weak grid such as distribution network, are sensitive to supply disturbances. While a majority of power produced in modern power systems comes from synchronous generators that have large inertias and whose control systems can compensate for slow power variations in the system, faster power variations at the scale of fraction of a second to the tens of seconds can seriously reduce reliability of power system operation. Energy storage integrated with wind turbines can address this challenge. In this dissertation, lithium-ion ultracapacitors are investigated as a potential solution for filtering power variations at the scale of tens of seconds. Another class of issues related to utilization of wind energy is related to economical operation of wind energy conversion systems. Wind speed variations create large mechanical loads on wind turbine components, which lead to their early failures. One of the most critical components of a wind turbine is a gearbox that mechanically couples turbine rotor and generator. Gearboxes are exposed to large mechanical load variations which lead to their early failures and increased cost of wind turbine operation and maintenance. This dissertation proposes a new critical load reduction strategy that removes mechanical load components that are the most dangerous in terms of harmful effect they have on a gearbox, resulting in more reliable operation of a wind turbine