Mitigation Of Negative Impedance Instabilities In Dc Distribution Systems

This book focuses on the mitigation of the destabilizing effects introduced by constant power loads (CPLs) in various non-isolated DC/DC converters and island DC microgrids using a robust non-linear sliding mode control (SMC) approach. This book validates theoretical concepts using real-time simulation studies and hardware implementations. Novel sliding mode controllers are proposed to mitigate negative impedance instabilities in DC/DC boost, buck, buck-boost, bidirectional buck-boost converters, and islanded DC microgrids. In each case, the condition for the large-signal stability of the converter feeding a CPL is established. An SMC-based nonlinear control scheme for an islanded DC microgrid feeding CPL dominated load is proposed so as to mitigate the destabilizing effect of CPL and to ensure system stability under various operating conditions. A limit on CPL power is also established to ensure system stability. For all proposed solutions, simulation studies and hardware implementations are provided to validate the effectiveness of the proposed sliding mode controllers.

This book is devoted to the optimum design of the DCT in a hybrid AC/DC microgrid, which takes into account not only the influence of different inductors/capacitors values, but also numerous design goals (i.e., VCG, efficiency, stability and so on). This book examines the DCT's design problem in detail. It begins by reviewing existing DCTs in, the hybrid AC/DC microgrid and their design problems. Following that, this book proposes a family of DCT optimization design approaches to ensure that the designed DCT has good power transmission and voltage regulation ability in the hybrid AC/DC microgrid, even when the actual inductors/capacitors values fluctuate with practical power and temperature. Following that, this book provides a family of multi-objective optimization design methodologies for the DCT to guarantee that it concurrently achieves the requirements of VCG, efficiency, and system stability. This book also covers how to control the DCT in a hybrid AC/DC microgrid optimally and generically.

Medium Voltage Direct Current Grid is the first comprehensive reference to provide advanced methods and best practices with case studies to Medium Voltage Direct Current Grid (MVDC) for Resilience Operation, Protection and Control. It also provides technical details to tackle emerging challenges, and discuss knowledge and best practices about Modeling and Operation, Energy management of MVDC grid, MVDC Grid Protection, Power quality management of MVDC grid, Power quality analysis and control methods, AC/DC, DC/DC modular power converter, Renewable energy applications and Energy storage technologies. In addition, includes support to end users to integrate their systems to smart grid. Covers advanced methods and global case studies for reference Provides technical details and best practices for the individual modeling and operation of MVDC systems Includes guidance to tackle emerging challenges and support users in integrating their systems to smart grids

This book reports on a set of advances relating to nonlinear observer design, with a special emphasis on high-gain observers. First, it covers the design of filters and their addition to the observer for reducing noise, a topic that has been so far neglected in the literature. Further, it describes the adaptive re-design of nonlinear observers to reduce the effect of parametric uncertainty. It discusses several limitations of classical methods, presenting a set of successfull solutions, which are mathematically formalised through Lyapunov stability analysis, and in turn validated via numerical simulations. In the second part of the book, two applications of the adaptive nonlinear observers are described, such in the estimation of the liquid water in a hydrogen fuel cell and in the solution of a common cybersecurity problem, i.e. false data injection attacks in DC microgrids. All in all, this book offers a comprehensive report on the state-of-the-art in nonlinear observer design for energy systems, including mathematical demonstrations, and numerical and and experimental validations.

DC MICROGRIDS Written and edited by a team of well-known and respected experts in the field, this new volume on DC microgrids presents the state-of-the-art developments and challenges in the field of microgrids for sustainability and scalability for engineers, researchers, academicians, industry professionals, consultants, and designers. The electric grid is on the threshold of a paradigm shift. In the past few years, the picture of the grid has changed dramatically due to the introduction of renewable energy sources, advancements in power electronics, digitalization, and other factors. All these megatrends are pointing toward a new electrical system based on Direct Current (DC). DC power systems have inherent advantages of no harmonics, no reactive power, high efficiency, over the conventional AC power systems. Hence, DC power systems have become an emerging and promising alternative in various emerging applications, which include distributed energy sources like wind, solar and Energy Storage System (ESS), distribution networks, smart buildings, remote telecom systems, and transport electrification like electric vehicles (EVs). All these applications are designed at different voltages to meet their specific requirements individually because of the lack of standardization. Thus, the factors influencing the DC voltages and system operation needed to be surveyed and analyzed, which include voltage standards, architecture for existing and emerging applications, topologies and control strategies of power electronic interfaces, fault diagnosis and design of the protection system, optimal economical operation, and system reliability.

Detect and Mitigate Transients in Electrical Systems This practical guide explains how to identify the origin of disturbances in electrical systems and analyze them for effective mitigation and control. Transients in Electrical Systems considers all transient frequencies, ranging from 0.1 Hz to 50 MHz, and discusses transmission line and cable modeling as well as frequency dependent behavior. Results of EMTP simulations, solved examples, and detailed equations are included in this comprehensive resource. Transients in Electrical Systems covers: Transients in lumped circuits Control systems Lightning strokes, shielding, and backflashovers Transients of shunt capacitor banks Switching transients and temporary overvoltages Current interruption in AC circuits Symmetrical and unsymmetrical short-circuit currents Transient behavior of synchronous generators, induction and synchronous motors, and transformers Power electronic equipment Flicker, bus, transfer, and torsional vibrations Insulation coordination Gas insulated substations Transients in low-voltage and grounding systems Surge arresters DC systems, short-circuits, distributions, and HVDC Smart grids and wind power generation