This paper discusses the modular multilevel cascade converter (MMCC) family based on cascade connection of multiple bidirectional chopper cells or single-phase full-bridge cells. The MMCC family is classified from circuit configuration as follows: the single-star bridge cells (SSBC); the single-delta bridge cells (SDBC); the double-star chopper cells (DSCC); and the double-star bridge cells (DSBC). The term MMCC corresponds to a family name in a person while, for example, the term SSBC corresponds to a given name. Therefore, the term “MMCC-SSBC” can identify the circuit configuration without any confusion. Among the four MMCC family members, the SSBC and DSCC are more practical in cost, performance, and market than the others although a distinct difference exists in application between the SSBC and DSCC. This paper presents application examples of the SSBC to a battery energy storage system (BESS), the SDBC to a static synchronous compensator (STATCOM) for negative-sequence reactive-power control, and the DSCC to a motor drive for fans and blowers, along with their experimental results.

Classification, Terminology, and Application of the Modular Multilevel Cascade Converter (MMCC)

With wide-spread application of power electronic systems across many different industries, their reliability is being studied extensively. This paper presents a comprehensive review of reliability assessment and improvement of power electronic systems from three levels: 1) metrics and methodologies of reliability assessment of existing system; 2) reliability improvement of existing system by means of algorithmic solutions without change of the hardware; and 3) reliability-oriented design solutions that are based on fault-tolerant operation of the overall systems. The intent of this review is to provide a clear picture of the landscape of reliability research in power electronics. The limitations of the current research have been identified and the direction for future research is suggested.

https://www.egr.msu.edu/~bingsen/files_publications/J-13_TPEL_Reliability.pdf

Survey on Reliability of Power Electronic Systems

With wide-spread application of power electronic converters in high power systems, there has been a growing interest in system reliability analysis and fault-tolerant capabilities. This paper presents a comprehensive review of conventional fault-tolerant techniques regarding power electronic converters in case of power semiconductor device failures. These techniques can be classified into four categories based on the type of hardware redundancy unit: switch-level, leg-level, module-level, and system-level. Also, various fault-tolerant methods are assessed according to cost, complexity, performance, etc. The intent of this review is to provide a detailed picture regarding the current landscape of research in power electronic fault-handling mechanisms.

Survey on Fault-Tolerant Techniques for Power Electronic Converters

This paper provides a chronological overview of the topology for multilevel converters, and discusses their different terminology usages and characteristics. The multilevel converters include three-level neutral-point-clamped (NPC) and neutral-point-piloted (NPP) inverters, three-level and four-level flying-capacitor (FLC) inverters, and a family of modular multilevel cascade converters. Some have already been put into commercial use, some have been on a research and development stage, and others have been on an academic research stage. This paper pays much attention to six family members of the modular multilevel cascade converters, intended for grid-tied applications and medium-voltage high-power motor drives.

Multilevel Converters: Fundamental Circuits and Systems

A smart city is a sustainable and efficient urban centre that provides a high quality of life to its inhabitants through optimal management of its resources. Energy management is one of the most demanding issues within such urban centres owing to the complexity of the energy systems and their vital role. Therefore, significant attention and effort need to be dedicated to this problem. Modelling and simulation are the major tools commonly used to assess the technological and policy impacts of smart solutions, as well as to plan the best ways of shifting from current cities to smarter ones. This paper reviews energy-related work on planning and operation models within the smart city by classifying their scope into five main intervention areas: generation, storage, infrastructure, facilities, and transport. More-complex urban energy models integrating more than one intervention area are also reviewed, outlining their advantages and limitations, existing trends and challenges, and some relevant applications. Lastly, a methodology for developing an improved energy model in the smart-city context is proposed, along with some additional final recommendations.

/pdf/energy-management-and-planning-in-smart-cities-2wvn91rr78.pdf

Energy management and planning in smart cities

The battery energy storage system is an essential enabling device of the smart grid, because it helps grid connection of massive renewable energy resources. This paper has a brief discussion on a battery energy storage system based on a multilevel cascade pulsewidth-modulated (PWM) converter for its practical use. The active-power control of individual converter cells is presented to make it possible to charge and discharge the battery units at different power levels while producing a three-phase balanced line-to-line voltage. This results in the maximum utilization of battery energy even when the power-handling capabilities of the battery units differ. Experimental results obtained from a 200-V, 10-kW, 3.6-kWh battery energy storage system verify the effectiveness of the presented active-power control.

Active-Power Control of Individual Converter Cells for a Battery Energy Storage System Based on a Multilevel Cascade PWM Converter

This paper focuses on fault-tolerant control for a battery-energy-storage system based on a multilevel cascade pulsewidth-modulation (PWM) converter with star configuration. During the occurrence of a single-converter-cell or single-battery-unit fault, the fault-tolerant control enables continuous operation and maintains state-of-charge balancing of the remaining healthy battery units. This enhances both system reliability and availability. A 200-V, 10-kW, 3.6-kW·h laboratory system combining a three-phase cascade PWM converter with nine nickel-metal-hydride battery units is designed, constructed, and tested to verify the validity and effectiveness of the proposed fault-tolerant control.

Fault-Tolerant Operation of a Battery-Energy-Storage System Based on a Multilevel Cascade PWM Converter With Star Configuration

This paper focuses on fault-tolerant control for a battery energy storage system based on a three-phase multilevel cascade PWM (pulse-width-modulation) converter with star configuration. It enables continuous operation and maintains SOC (state-of-charge) balancing of operating battery units even during the occurrence of a converter-cell or battery-unit failure. This enhances both system reliability and availability. A 200-V, 10-kW, 3.6-kWh laboratory system combining a three-phase cascade PWM converter with nine NiMH (Nickel-metal-hydride) battery units is designed, constructed, and tested to verify the validity and effectiveness of the proposed fault-tolerant control.

Fault-tolerant control for a battery energy storage system based on a cascade PWM converter

This paper makes discussions on a battery energy storage system based on a multilevel cascade pulsewidth-modulated (PWM) converter for its practical use. Briefly discussed are several considerations including state-of-charge (SOC) balancing of multiple battery units, and fault tolerance of the system. An active-power control of individual converter cells is presented to make the multiple battery units charged or discharged at different power levels, producing a three-phase balanced line-to-line voltage. Experimental results obtained from a 200-V, 10-kW, 3.6-kWh battery energy storage system verify its effectiveness.

Tsukasa Yamagishi

Papers

Active-Power Control of Individual Converter Cells for a Battery Energy Storage System Based on a Multilevel Cascade PWM Converter

Fault-Tolerant Operation of a Battery-Energy-Storage System Based on a Multilevel Cascade PWM Converter With Star Configuration

Fault-tolerant control for a battery energy storage system based on a cascade PWM converter

Discussions on a battery energy storage system based on a cascade PWM converter with star configuration