Robust Control For Grid Voltage Stability High Penetration Of Renewable Energy

This book makes the area of integration of renewable energy into the existing electricity grid accessible to engineers and researchers. This is a self-contained text which has models of power system devices and control theory necessary to understand and tune controllers in use currently. The new research in renewable energy integration is put into perspective by comparing the change in the system dynamics as compared to the traditional electricity grid. The emergence of the voltage stability problem is motivated by extensive examples. Various methods to mitigate this problem are discussed bringing out their merits clearly. As a solution to the voltage stability problem, the book covers the use of FACTS devices and basic control methods. An important contribution of this book is to introduce advanced control methods for voltage stability. It covers the application of output feedback methods with a special emphasis on how to bound modelling uncertainties and the use of robust control theory to design controllers for practical power systems. Special emphasis is given to designing controllers for FACTS devices to improve low-voltage ride-through capability of induction generators. As generally PV is connected in low voltage distribution area, this book also provides a systematic control design for the PV unit in distribution systems. The theory is amply illustrated with large IEEE Test systems with multiple generators and dynamic load. Controllers are designed using Matlab and tested using full system models in PSSE.

This thesis addresses the frequency and voltage stability issues of stand-alone microgrids with high penetration of renewable energy by making use of energy storage devices, and is divided into two main parts.In the first part, we propose a systematic design of a multi-variable robust control structure for frequency regulation in a diesel-photovoltaic-supercapacitor hybrid power generation system operating in stand-alone mode. The proposed control structure relies on a two-level architecture: classical PI-based current tracking controllers are placed on the low control level and receive references from an H-infinity-control-based upper level. A comprehensive methodology that casts the specific engineering demands of microgrid operation into H-infinity control formalism is detailed. It is also shown how closed-loop dynamic performance requirements must at their turn be taken into account in the initial microgrid setup and sizing, namely in appropriately choosing and rating the energy storage system. Then, a robust performance analysis of the synthesized H-infinity controller in the presence of various load disturbances, photovoltaic output active power variations, and model uncertainties is carried out in order to determine the maximum parameter variation range for which the imposed control performances are respected for the considered operating point. Numerical simulations performed with MATLAB/Simulink show the effectiveness of the proposed frequency robust control strategy on a MVA-rated microgrid. A rapid-prototyping test bench, which is composed of a real supercapacitor-based energy storage system and an emulated diesel-photovoltaic-load grid, is developed in order to experimentally validate this control strategy.The second part of this thesis focuses on computing an H-infinity-based multi-variable voltage controller in order to robustly force the voltage magnitude of the point of common coupling to satisfy dynamic specifications. The same idea of cascaded two-level control structure - where this controller is placed on an upper control level and provides the references to current controllers placed on a lower level - is aslo adopted. Then, the performance and robustness of the proposed H-infinity controller in the presence of various load and photovoltaic reactive power disturbances, as well as model uncertainties, are studied based on MATLAB/Simulink time-domain simulations.

To meet the increasing demand of electrical power, the use of renewable energy-based smart grid is attracting significant attention in recent years throughout the world. The high penetration of renewable power in the smart grids is growing its importance due to its non-finishing, reusable, reliable, sustainable, lower cost, and available characteristics. The renewable energy-based smart grid technology may mitigate the increasing energy demands effectively and efficiently without hampering the environment. But the uncertain nature of renewable sources largely affects the operation of the smart grid by un-stabling the voltage and frequency that may introduces power quality and reliability problems, which requires special control techniques. This book investigates the challenges in controlling renewable energy-based smart grids and proposes different control techniques to control the voltage and frequency effectively to improve the power quality and reliability of the power grids. This book is a valuable resource for readers interested in practical solutions in smart grids and renewable energy systems.

This book presents advanced control techniques that use neural networks to deal with grid disturbances in the context renewable energy sources, and to enhance low-voltage ride-through capacity, which is a vital in terms of ensuring that the integration of distributed energy resources into the electrical power network. It presents modern control algorithms based on neural identification for different renewable energy sources, such as wind power, which uses doubly-fed induction generators, solar power, and battery banks for storage. It then discusses the use of the proposed controllers to track doubly-fed induction generator dynamics references: DC voltage, grid power factor, and stator active and reactive power, and the use of simulations to validate their performance. Further, it addresses methods of testing low-voltage ride-through capacity enhancement in the presence of grid disturbances, as well as the experimental validation of the controllers under both normal and abnormal grid conditions. The book then describes how the proposed control schemes are extended to control a grid-connected microgrid, and the use of an IEEE 9-bus system to evaluate their performance and response in the presence of grid disturbances. Lastly, it examines the real-time simulation of the entire system under normal and abnormal conditions using an Opal-RT simulator.

Power systems are evolving towards the Smart Grid paradigm, featured by large-scale integration of renewable energy resources, e.g. wind and solar power, deeper participation of demand side, and enhanced interaction with electric vehicles. While these emerging elements are inherently stochastic in nature, they are creating a challenge to the system’s stability and its control. In this context, conventional analysis tools are becoming less effective, and necessitate the use alternative tools that are able to deal with the high uncertainty and variability in the smart grid. Smart Grid initiatives have facilitated wide-spread deployment of advanced sensing and communication infrastructure, e.g. phasor measurement units at grid level and smart meters at household level, which collect tremendous amount of data in various time and space scales. How to fully utilize the data and extract useful knowledge from them, is of great importance and value to support the advanced stability assessment and control of the smart grid. The intelligent system strategy has been identified as an effective approach to meet the above needs. This book presents the cutting-edge intelligent system techniques and their applications for stability assessment and control of power systems. The major topics covered in this book are: Intelligent system design and algorithms for on-line stability assessment, which aims to use steady-state operating variables to achieve fast stability assessment for credible contingencies. Intelligent system design and algorithms for preventive stability control, which aims at transparent and interpretable decision-making on preventive control actions to manipulate system operating condition against possible contingencies. Intelligent system design and algorithms for real-time stability prediction, which aims to use synchronized measurements to foresee the stability status under an ongoing disturbance. Intelligent system design and algorithms for emergency stability control, which aims at fast decision-making on stability control actions at emergency stage where instability is propagating. Methodologies and algorithms for improving the robustness of intelligent systems against missing-data issues. This book is a reference and guide for researchers, students, and engineers who seek to study and design intelligent systems to resolve stability assessment and control problems in the smart grid age.

Advanced Frequency Regulation Strategies in Renewable-Dominated Modern Power Systems discusses advanced control strategies positioned to attain stable and reliable electric power operation in highly renewable modern grids. These strategies are increasingly valuable components of the practitioner technical toolbox, and are essential to maintain frequency and voltage regulations, assert power quality standards, and ensure overall grid stability. This book focuses on the rapid integration of renewable-based generating units in power systems, highlighting state-of-the-art technologies and emerging topics pertaining to load frequency control, robust control strategies, and energy storage systems. Chapters are accompanied by case studies drawn from modern international practice. Disseminates novel control strategies for the reliable and robust control of renewable generating units Discusses implementation using case studies that address multiple frequency control applications across integrated modern power systems Accompanied by simulation models in MATLAB that are built to emphasize practical usage and address real-world problems

This book proposes new control and protection schemes to improve the overall stability and security of future wide-area power systems. It focuses on the high penetration levels of renewable energy sources and distributed generation, particularly with the trend towards smart grids. The control methods discussed can improve the overall stability in normal and abnormal operation conditions, while the protection methods presented can be used to ensure the secure operation of systems under most severe contingencies. Presenting stability, security, and protection methods for power systems in one concise volume, this book takes the reader on a journey from concepts and fundamentals to the latest and future trends in each topic covered, making it an informative and intriguing read for researchers, graduate students, and practitioners alike.