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<p><i>Design, Control and Application of Modular Multilevel Converters for HVDC Transmission Systems&nbsp;</i>is a comprehensive guide to semiconductor technologies applicable for MMC design, component sizing control, modulation, and application of the MMC technology for HVDC transmission.</p> <p>Separated into three distinct parts, the first offers an overview of MMC technology, including information on converter component sizing, Control and Communication, Protection and Fault Management, and Generic Modelling and Simulation. The second covers the applications of MMC in offshore WPP, including planning, technical and economic requirements and optimization options, fault management, dynamic and transient stability. Finally, the third chapter explores the applications of MMC in HVDC transmission and Multi Terminal configurations, including Supergrids.</p> <p>Key features:</p> <ul> <li>Unique coverage of the offshore application and optimization of MMC-HVDC schemes for the export of offshore wind energy to the mainland.</li> <li>Comprehensive explanation of MMC application in HVDC and MTDC transmission technology.</li> <li>Detailed description of MMC components, control and modulation, different modeling approaches, converter dynamics under steady-state and fault contingencies including application and housing of MMC in HVDC schemes for onshore and offshore.</li> <li>Analysis of DC fault detection and protection technologies, system studies required for the integration of HVDC terminals to offshore wind power plants, and commissioning procedures for onshore and offshore HVDC terminals.</li> <li>A set of self-explanatory simulation models for HVDC test cases is available to download from the companion website.</li> </ul> <p>This book provides essential reading for graduate students and researchers, as well as field engineers and professionals who require an in-depth understanding of MMC technology.</p> <div>&nbsp;</div>

Advancements in grid converter technology have been pivotal in the successful integration of renewable energy. The high penetration of renewable energy systems is calling for new more stringent grid requirements. As a consequence, the grid converters should be able to exhibit advanced functions like: dynamic control of active and reactive current injection during faults, and grid services support. <p>This book explains the topologies, modulation and control of grid converters for both photovoltaic and wind power applications. In addition to power electronics, coverage focuses on the specific applications in photovoltaic and wind power systems where grid condition is an essential factor.</p> <p>With a review of the most recent grid requirements for photovoltaic and wind power systems, the relevant issues are discussed:</p> <ul> <li> <div>Modern grid inverter topologies for photovoltaic and wind turbines</div> </li> <li> <div>Islanding detection methods for photovoltaic systems</div> </li> <li> <div>Synchronization techniques based on second order generalized integrators (SOGI)</div> </li> <li> <div>Advanced synchronization techniques with robust operation under grid unbalance condition</div> </li> <li> <div>Resonant controller techniques for current control and harmonic compensation</div> </li> <li> <div>Grid filter design and active damping techniques</div> </li> <li> <div>Power control under grid fault conditions, considering both positive and negative sequences</div> </li> </ul> <p>Throughout, the authors include practical examples, exercises, and simulation models and an accompanying website sets out further modeling techniques using MATLAB&#174; and Simulink environments and physical security information management (PSIM) software.</p> <p><i>Grid Converters for Photovoltaic and Wind Power Systems</i> is intended as a course book for graduate students with a background in electrical engineering and for professionals in the evolving renewable energy industry. For professors interested in adopting the course, a set of slides is available for download from the website.</p> <p><b>Companion Website</b></p> <p><a href=\"http://www.wiley.com/go/grid_converters\">www.wiley.com/go/grid_converters</a></p>

As a critical indictor in the Battery Management System (BMS), State of Charge (SOC) is closely related to the reliable and safe operation of lithium-ion (Li-ion) batteries. Model-based methods are an effective solution for accurate and robust SOC estimation, the performance of which heavily relies on the battery model. This paper mainly focuses on battery modeling methods, which have the potential to be used in a model-based SOC estimation structure. Battery modeling methods are classified into four categories on the basis of their theoretical foundations, and their expressions and features are detailed. Furthermore, the four battery modeling methods are compared in terms of their pros and cons. Future research directions are also presented. In addition, after optimizing the parameters of the battery models by a Genetic Algorithm (GA), four typical battery models including a combined model, two RC Equivalent Circuit Model (ECM), a Single Particle Model (SPM), and a Support Vector Machine (SVM) battery model are compared in terms of their accuracy and execution time.

With widespread applications for lithium-ion batteries in energy storage systems, the performance degradation of the battery attracts more and more attention. Understanding the battery’s long-term aging characteristics is essential for the extension of the service lifetime of the battery and the safe operation of the system. In this paper, lithium iron phosphate (LiFePO4) batteries were subjected to long-term (i.e., 27–43 months) calendar aging under consideration of three stress factors (i.e., time, temperature and state-of-charge (SOC) level) impact. By means of capacity measurements and resistance calculation, the battery’s long-term degradation behaviors were tracked over time. Battery aging models were established by a simple but accurate two-step nonlinear regression approach. Based on the established model, the effect of the aging temperature and SOC level on the long-term capacity fade and internal resistance increase of the battery is analyzed. Furthermore, the storage life of the battery with respect to different stress factors is predicted. The analysis results can hopefully provide suggestions for optimizing the storage condition, thereby prolonging the lifetime of batteries.

Lithium-ion (Li-ion) batteries have been competitive in Electric Vehicles (EVs) due to their high energy density and long lifetime. However, there are still issues, which have to be solved, related to the fast-charging capability of EVs. The pulsed current charging technique is expected to improve the lifetime, charging speed, charging/discharging capacity, and the temperature rising of Li-ion batteries. However, the impact of the pulsed current parameters (i.e., frequency, duty cycle, and magnitude) on characteristics of Li-ion batteries has not been fully understood yet. This paper summarizes the existing pulsed current modes, which are positive Pulsed Current Mode (PPC) and its five extended modes, and Negative Pulsed Current (NPC) mode and its three extended modes. An overview of the impact of pulsed current techniques on the performance of Li-ion batteries is presented. Then the main impact factors of the PPC strategy and the NPC strategy are analyzed and discussed. The weight of these impact factors on lifetime, charging speed, charging/discharging capacity, and the temperature rising of batteries is presented, which provides guidance to design advanced charging/discharging strategies as well as to determine future research gaps.

A modular multilevel converter’s (MMC’s) submodule (SM)-capacitor voltage will increase under unbalanced grid conditions. Depending on the imbalance level, the voltage ripple can be considerably high, and it can exceed the pre-defined safe limits. If this occurs, the converter will trip, which can lead to serious stability problems for the grid. This paper first proposes an analytical solution for deriving the three-phase imbalanced SM ripple of an MMC under an unbalanced grid. With this analytical tool, the imbalance mechanism of the SM voltage ripple can be easily understood. What is more, the symmetrical component method is first applied to analyze the three-phase SM capacitor ripple, and the positive-/negative-/zero-sequence components of the three-phase SM voltage ripple are easily identified by the proposed analytical method. Then, based on this powerful analytical tool, the proper circulating-current profile to be injected can be obtained, allowing for the right compensation of the voltage ripple. Based on this approach, two new voltage ripple compensation methods are proposed in this paper. Simulations were carried out to validate the analytical description of the submodule-capacitor voltage ripple proposed in this paper. Moreover, simulation and experimental results are provided to validate the new compensation techniques introduced in this paper.

The worldwide energy revolution has accelerated the utilization of demand-side manageable energy systems such as wind turbines, photovoltaic panels, electric vehicles, and energy storage systems in order to deal with the growing energy crisis and greenhouse emissions. The control system of renewable energy units and energy storage systems has a high effect on their performance and absolutely on the efficiency of the total power network. Classical controllers are based on integer-order differentiation and integration, while the fractional-order controller has tremendous potential to change the order for better modeling and controlling the system. This paper presents a comprehensive review of the energy system of renewable energy units and energy storage devices. Various papers are evaluated, and their methods and results are presented. Moreover, the mathematical fundamentals of the fractional-order method are mentioned, and the various studies are categorized based on different parameters. Various definitions for fractional-order calculus are also explained using their mathematical formula. Different studies and numerical evaluations present appropriate efficiency and accuracy of the fractional-order techniques for estimating, controlling, and improving the performance of energy systems in various operational conditions so that the average error of the fractional-order methods is considerably lower than other ones.

In this paper, the concept of smart battery pack is introduced. The smart battery pack is based on wireless feedback from individual battery cells and is capable to be applied to electric vehicle applications. The proposed solution increases the usable capacity and prolongs the life cycle of the batteries by directly integrating the battery management system in the battery pack. The battery cells are connected through half-bridge chopper circuits, which allow either the insertion or the bypass of a single cell depending on the current states of charge. This consequently leads to the balancing of the whole pack during both the typical charging and discharging time of an electric vehicle and enables the fault-tolerant operation of the pack. A wireless feedback for implementing the balancing method is proposed. This solution reduces the need for cabling and simplifies the assembling of the battery pack, making also possible a direct off-board diagnosis. The paper validates the proposed smart battery pack and the wireless feedback through simulations and experimental results by adopting a battery cell emulator.

The modular multilevel converter is capable to reach high-voltage levels with high flexibility, high reliability, and high power quality as it became the standard solution for high-power high-voltage applications that operate with fixed frequency. However, in machine-drive applications, the modular multilevel converter shows critical problems since an extremely high submodule-capacitor voltage ripple occurs in the machine start-up and at low-speed operation, which can damage the converter. Recently, a new converter solution named modular multilevel series converter was proposed as a promising alternative for high-power machine-drive applications since it presented many important structural and operational advantages in relation to the modular multilevel converter such as the reduced number of submodule capacitors and the low submodule-capacitor voltage ripple at low frequencies. Even though the modular multilevel series converter presented a reduced number of capacitors, the size of these capacitors was not analyzed. This paper presents a detailed comparison analysis of the performance of the modular multilevel converter and the modular multilevel series converter at variable-frequency operation, which is based on the proposed analytical description of the submodule-capacitor voltage ripple in such topologies. This analysis concludes that the new modular multilevel series converter can be designed with smaller capacitors in comparison to the modular multilevel converter if these converters are used to drive electrical machines that operate within a range of low-frequency values. In other words, the modular multilevel series converter experiences extremely low submodule-capacitor voltage ripple at very low frequencies, which means that this converter solution presents high performance in the electrical machine start-up and at low-speed operation.

In recent years, the integration of the high-power static synchronous compensator (STATCOM) and energy storage in the same device has gained interest. Such a system is referred to as ES-STATCOM. Modular multilevel converter (MMC) topologies constitute a promising converter family for ES-STATCOM realization, providing a modular and scalable solution with a high efficiency that handles high-power and high-voltage ratings in grid applications. There is a gap in technical literature discussing the design and the comparison of MMC-based ES-STATCOMs while utilizing batteries to find the most suitable MMC topology for ES-STATCOMs. Therefore, this paper benchmarks MMC family members for ES-STATCOM realization. Both centralized and distributed energy storage approaches are investigated. The proposed design flowcharts can be employed for comparison and optimization purposes. In total, seven topologies are compared in terms of number of cells, required silicon area and total battery volume. Different semiconductor devices and battery types are analyzed. The result indicates that centralized energy storage systems are the most suitable due to their design flexibility, low volume and small silicon area. Moreover, the possibility of using over-modulation in MMC using bridge cells has an important role in the optimization of ES-STATCOM. The results for the adopted case study shows that the decentralized approach can lead to 55% higher silicon area and 30% higher volume than the centralized approach. The double-star bridge cell MMC with centralized energy storage is determined as the most suitable solution for ES-STATCOM systems.