دانلود کتاب ریزشبکه‌ها شامل حفاظت و پایداری منابع هیبریدی

The electric power system is undergoing a major transformation driven by the increasing penetration of distributed energy resources, renewable energy technologies, energy storage systems, and advanced power electronic converters. As power systems evolve from centralized hierarchical structures toward more decentralized architectures, microgrids have emerged as one of the most promising solutions for improving reliability, resiliency, efficiency, and sustainability. The growing demand for electrical energy, together with the need to reduce operating costs, minimize losses, improve efficiency, and enhance service reliability, has accelerated the deployment of distributed generation resources throughout modern distribution networks. Today, distributed generators are widely used in residential, commercial, and industrial facilities. Among the most common technologies are synchronous-generator-based resources, such as diesel generators and gas engines, and inverter-based distributed generations, such as photovoltaic and battery energy storage systems. Historically, distributed generators were mainly operated in grid-connected mode, where the utility network maintained system voltage and frequency while local generators supplied part of the demand. In recent years, however, their role has expanded considerably. Modern microgrids are increasingly expected to continue supplying critical and essential loads during utility outages through islanded operation. Consequently, reliable performance under both grid-connected and islanded conditions has become one of the primary requirements of modern microgrid design and operation. Moreover, in many practical applications, different distributed generation technologies operate together within the same microgrid. Such hybrid structures allow operators to exploit the advantages of multiple energy sources while improving flexibility and reliability. At the same time, they introduce new technical challenges associated with system dynamics, stability, control, and protection. Among these challenges, stability is one of the most critical issues. Modern microgrids often contain a combination of synchronous generators and inverter-based resources whose dynamic characteristics differ significantly. While synchronous generators inherently contribute electromechanical inertia and support system stability, inverter-based resources depend largely on control algorithms and power electronic converters to regulate their behavior. Consequently, many conventional methods of stability assessment and control design must be revised to accommodate the characteristics of converter-dominated systems. Moreover, protection represent another essential aspect of microgrid operation. A properly designed protection system must rapidly detect faults and abnormal operating conditions while maintaining adequate security and dependability against non-faulty conditions. The integration of distributed generators changes fault-current signatures including magnitude and phase, alters power-flow patterns, and introduces bidirectional current paths that may affect the performance of conventional protection schemes. These challenges have motivated the development of new protection philosophies, especially for setting adjustments and adaptive approaches capable of maintaining reliable operation under changing system conditions. Modern distributed generation technologies are increasingly capable of supporting utility systems through voltage regulation, frequency support, disturbance ride-through capability, and enhanced system resiliency. Therefore, properly designed microgrids can serve not only as beneficial local energy systems but also as valuable assets for the broader power network. The primary motivation behind writing this book is to provide a comprehensive and practically oriented treatment of protection and stability of microgrids that integrates both synchronous-generator based and inverter-based technologies within a unified framework. Although numerous publications discuss distributed generations, renewable energy systems, and microgrid control, relatively few references address protection-system design, stability assessment, islanding detection, and stability enhancement in an integrated manner. This book seeks to bridge that gap by combining fundamental concepts, analytical methods, and practical engineering considerations within a single reference. In addition, the book has been developed with a strong educational perspective. It is intended to serve as a valuable resource for both undergraduate and graduate students, researchers, and practicing engineers who are involved in the analysis, planning, design, operation, and protection and stability studies of modern microgrids. By providing detailed models, engineering insights, solved examples and practical methodologies, the book aims to support both advanced academic studies and professional engineering practice. To help the readers better comprehend the provided material, different problems are provided at the end of each chapter. In addition, simulation files for some sample distribution systems are provided in the book companion website. Moreover, the supplied presentation slides in the website would help the instructors to teach the book material more efficiently. It is our hope that the material presented herein will assist readers in developing a deeper understanding of microgrid behavior and enable them to design more reliable, secure, and resilient microgrid systems in an increasingly decentralized power industry. To achieve this objective, the book is organized into six chapters. Chapter 1 introduces the major fundamentals and basic structure of distributed generation technologies employed in modern microgrids, including photovoltaic systems, wind generation technologies, small scale synchronous generators, and inverter-based distributed generators. The chapter also presents dynamic models, control structures, and protection architectures that form the foundation for subsequent discussions. Chapter 2 focuses on the stability of synchronous-generator-based microgrids. Various forms of stability are defined and analyzed, together with the associated control systems and assessment methodologies. Control system and power supply stability, voltage and frequency stability, as well as transient stability are studied carefully and induction motor instability detection is discussed. The chapter also investigates dynamic phenomena that may threaten stable operation under different operating conditions. Chapter 3 examines the stability of inverter-based microgrids. Particular attention is devoted to inverter control systems, grid following and grid-forming strategies, synchronization mechanisms, transient stability, and small-signal stability. The implications of the control systems behavior on modern protection schemes are also discussed. In addition, various power and current control loops as well as different phenomena including voltage disturbance ride through and fault-induced delayed voltage recovery are investigated. Chapter 4 addresses the challenges associated with microgrid protection systems. Widely used protection schemes are reviewed, and practical issues such as relay miscoordination, sympathetic tripping, reduced protection sensitivity, unsuccessful reclosing operations, and the limitations of conventional load-shedding methods are investigated. Moreover, various concepts such as backup and loss of field protection, as well as synchronous generator- based and inverter-based distributed generations protection challenges are discussed. Chapter 5 investigates islanding detection in both synchronous generator- based and inverter-based microgrids. Various local/remote and active/passive detection techniques are evaluated using appropriate performance criteria, and their applicability to different microgrid configurations is discussed. Different concepts such as non detection zone, islanding detection time and unsymmetrical islanding are studied. Several approaches for improving islanding detection performance are also presented. Chapter 6 presents practical methods for enhancing both microgrid protection and stability. Relay-setting methodologies, adaptive protection schemes, solutions for back-feed, sympathetic tripping and fault-induced delayed voltage recovery are discussed. Advanced approaches for improving system security, dependability, and resiliency are reviewed together with practical solutions for improving microgrid stability during severe disturbances.