Meshed Multi-Terminal Direct Current (MMTDC) Grid Protection and Control

近几十年来，全球对气候变化的关注与日俱增。为了实现能源部门的脱碳和更可持续的能源系统，应增加可再生资源在整个能源组合中的份额。风能是生产清洁能源的低成本替代能源之一，并提供了一种对冲更高的碳燃料成本的手段。最近，在风力发电项目上进行了大量投资。2014年，加拿大安大略省、魁北克省、艾伯塔省、新斯科舍省和爱德华王子岛共安装了37个风力发电项目，总装机容量为1871兆瓦。随着今年安大略省270兆瓦风力发电项目的安装，加拿大的风力发电装机容量最近已超过10千兆瓦。可再生资源的大规模整合，特别是风能，给电力系统的运行带来了各种挑战，并正在推动对改变现有输电基础设施的研究。*电力的输电主要依赖交流(AC)技术。在很长的距离内，交流线路的输电能力会大大降低。高压交流技术的替代方案是高压直流输电(HVDC)。高压直流输电是一种环保的低损耗远距离输电技术，具有成本低、视觉效果好、杆塔和输电线路所需空间较少(与交流相比)等优点。除了加拿大现有的高压直流输电线路，如魁北克-新英格兰、纳尔逊河和温哥华岛，还有几条线路正在建设中，包括：艾伯塔省西部和东部(预计在2016年)、拉布拉多岛(预计在2017年)和海事(预计在2017年)。随着高压直流输电线路数量的增加，预计从长远来看，将建立一个网状多端直流(MMTDC)电网并覆盖交流输电系统。这一电网将使交流和高压直流输电系统能够吸收和经济地将新能源从可再生资源转移到偏远的负荷中心。*MMTDC电网在实践中尚未建成。制造商和系统运营商正在努力克服几个技术限制，以促进MMTDC电网的实现。保护、控制和互操作性是最具挑战性的问题。拟议的研究将克服这些挑战，并将为未来实现MMTDC电网以及它将给社会带来的所有好处铺平道路，包括：提高电力系统可靠性，降低换流器额定值和成本，降低备用容量，减少风能削减，增加邻国之间的电力交易。此外，通过这项研究计划，几名研究生和本科生将接受专门技能和热门技能的培训。

In recent decades, there has been a worldwide growing attention towards climate change. To move towards the decarbonisation of the energy sector and a more sustainable energy system, the share of renewable resources in the overall energy mix should be increased. Wind energy is one of the low-cost alternatives for generating clean energy and provides a hedge against higher carbon fuel costs. Recently, significant investments have been made in wind generation projects. In 2014, 37 wind power projects, totaling a production of 1871 MegaWatts (MWs), were installed in the Canadian provinces of Ontario, Quebec, Alberta, Nova Scotia and Prince Edward Island. With this year's installation of the 270 MWs wind project in Ontario, Canada's installed wind generation has recently surpassed 10 GigaWatts. The large integration of renewable resources, in particular wind energy, poses various challenges to the operation of the electrical power system, and is driving research into changing the existing transmission infrastructure.***Transmission of electrical power primarily relies on alternating current (AC) technology. Over long distances, the power transmission capacity of AC lines is drastically reduced. The alternative to high voltage AC technology is high voltage direct current (HVDC). HVDC is an environment-friendly low loss power transmission technology and over long distances, offers lower costs and visual impact and requires less space for towers and transmission lines (compared to AC). Besides the existing HVDC lines in Canada such as Quebec-New England, Nelson River and Vancouver Island, several more lines are under construction, including: Western and Eastern Alberta (expected in 2016), Labrador-Island (expected in 2017) and Maritime (expected in 2017). With the increase in the number of HVDC lines, it is envisioned that, in the long run, a meshed multi-terminal DC (MMTDC) grid will be built and overlay the AC transmission system. This grid will allow the combined AC and HVDC transmission system to absorb and economically transfer new sources of energy generation from renewable resources to remote load centres. ***An MMTDC grid has not been built in practice yet. There are several technical limitations that manufacturers and system operators are trying to overcome to facilitate the realization of an MMTDC grid. Protection, control and interoperability are among the most challenging questions. The proposed research will overcome these challenges and will pave the road for future realization of an MMTDC grid and all the benefits that it will bring to the society, including: improved electric system reliability, reduced converter ratings and costs, lower reserve capacity, reduced wind curtailment and increased power trading among neighboring countries. Furthermore, through this research program, several graduate and undergraduate students will be trained in specialized and sought after skills.**************************