Series Connection of Power Devices for Modular Multilevel Converter based High Voltage Direct Current Transmissions

随着电力消耗的持续增长，对长距离大容量电力传输的需求显著增加。 与传统的交流解决方案相比，高压直流输电具有许多优点，例如效率更高、成本更低和尺寸更小。 高压直流输电技术经历了几代人的发展，再加上形成换流站骨干的功率器件的发展。 最新一代基于电压源转换器，由完全可控的硅器件实现，提供了巨大的灵活性。 然而，这些设备的可用电压容量极大地限制了系统电压水平，这进而限制了传输容量和效率。 针对这些问题，本计画将发展一种具有几乎零损耗及简单自平衡与同步演算法的串联机制，并将其应用于以模块化多电平换流器为基础的高压直流输电系统。 所开发的技术可以潜在地改变许多其他高功率电子应用，例如医疗设备的电源，工业电机驱动器和聚变动力反应堆的脉冲电源。 这些应用将影响社会的各个方面，并促进清洁和绿色能源的使用。 拟议的项目本质上是全面的，涉及电力工程的不同方面，从器件，电路到系统级研究，这将为下一代学生和工程师提供独特和高质量的培训。 本项目的目的是开发一种新型的串联功率器件连接技术，并探讨其在模块化多电平换流器中的应用，以应用于高压直流输电。 它通过简单可靠的拓扑结构和电压自平衡算法解决了串联连接功率器件时最具挑战性的问题。 对拟议项目的应用导向研究将产生关于组件尺寸、权衡和优化研究以及系统级实施的关键知识。 此外，碳化硅器件的串联连接将被评估。 待开发的多个原型将为真实的实施、理论分析的验证提供工程经验和指导，并且可以用作电路和系统级原型的构建块。 功率器件的串联连接将推进模块化多电平变换器技术，提高额定电压，减少子模块数量，并减少无源元件的尺寸。 本计画将改变以模块化多电平换流器为基础之高压直流输电之实现方式。

As the electricity consumption continues to grow, the need for long distance bulk power transmission has increased significantly. Compared to traditional ac solutions, high voltage dc transmissions offer a number of advantages such as higher efficiency, lower cost, and smaller size. The high voltage dc transmission technologies have experienced a number of generations coupled with the development of power devices which form the backbone of the converter stations. The latest generation is based on voltage source converters enabled by fully controllable silicon devices that offer tremendous flexibility. However, the available voltage capacity of these devices has greatly limited the system voltage levels, which then limits the transmission capacity and efficiency. To address these issues, this project will develop a series connection mechanism featured by almost zero loss and simple self-balancing and synchronization algorithm, as well as its implementation in modular multilevel converter based high voltage dc transmission systems. The developed techniques can potentially transform many other high power electronics applications such as power supplies for medical equipment, industrial motor drives, and pulsed power supplies for fusion power reactors. These applications will impact various aspects of the society and promote the usage of clean and green energy. The proposed project is intrinsically comprehensive involving different facets of power engineering ranging from device, circuit, to system level research, which will provide unique and high quality training for the next generation students and engineers. The proposed educational activities will also broaden the participation of women and other under-represented groups.The objectives of this project are to develop a novel series power device connection technique and explore its implementation in modular multilevel converter with applications in high voltage dc transmissions. It addresses the most challenging issues in connecting power devices in series with a simple and reliable topology and voltage self-balancing algorithm. The application oriented study of the proposed project will generate critical knowledge regarding component sizing, trade-off and optimization study, and system level implementation. Moreover, series connection of silicon carbide devices will be evaluated. The multiple prototypes to be developed will provide engineering experience and guidelines for real implementation, verification of the theoretical analysis, and can be used as building blocks for circuit and system level prototypes. The series connection of power devices will advance the modular multilevel converter technology with increased voltage rating, reduced sub-module count, and reduced size of passive components. This project will transform the realization of modular multilevel converter based high voltage dc transmissions.