AC-DC Hybrid Electric Power Systems

一个多世纪以来，电力系统已经演变成一种能量产生和分配完全以交流电（AC）形式；尽管高压直流输电（HVDC）在特定情况下被使用，但输电系统仍然主要是交流。这是因为，尽管爱迪生的早期直流电力系统有很多优点，但它在与交流电力系统的战斗中失败了，主要原因是缺乏“直流变压器”，因此在长距离部署时能量损失太大。然而，近年来，高效电子能量转换的进展重新引起了人们对直流电力系统的兴趣，以补充现有的交流系统。直流电源在海底电力传输方面更优越，例如来自海上风力发电场的电力传输。此外，大多数储能设备和现代发电机（如光伏系统、风力涡轮机和燃料电池）可以更方便、更有效地与直流基础设施相连接。此外，电能的消耗主要以直流形式发生。另一方面，交流电源具有独特的优点，是现有电力基础设施和设备的基础。因此，人们相信，未来的电力系统将受益于直流和交流电源的结合。因此，本研究的总体目标是研究交直流共存的混合电力系统。更具体地说，这项研究将发展和确定：

For more than a century, the electric power system has evolved into one in which energy is generated and distributed exclusively in the Alternating Current (AC) form; even though High-Voltage Direct Current (HVDC) transmission has been used in specific cases, the transmission system is nonetheless predominantly AC. This is because, despite its merits, Edison's early DC electric power system lost the battle to its AC counterpart, mainly due to the lack of a "DC transformer" and consequent prohibitively large energy losses for long-distance deployment. In recent years, however, advancements in efficient electronic energy conversion have renewed interests in DC electric power systems to supplement the existing AC system. DC power is superior when it comes to sub-sea power transmission, from offshore wind farms for example. Moreover, most energy storage devices and modern electric power generators (such as photovoltaic systems, wind turbines, and fuel cells) can more conveniently and efficiently be interfaced with a DC infrastructure. Furthermore, the consumption of electric energy primarily takes place in the DC form. On the other hand, AC power possesses distinct merits and is the foundation of the existing electric power infrastructure and equipment. Hence, it is believed that the power system of the future will benefit from a combination of both DC and AC powers. The overall objective of the proposed research is thus to study hybrid electric power systems in which AC and DC coexist. More specifically, the research will develop and identify: