Advancing Steady-State and Dynamic Operation of Islanded Hybrid AC-DC Microgrids

在过去的十年里，通过电力电子变流器将基于直流的分布式发电(DG)与电网中的负荷进行集成的情况出现了前所未有的增长。这既是一个挑战，因为所需的DC/AC和AC/DC转换阶段带来了额外的损耗，也为通过实施直流电网和消除不必要的转换阶段来提高效率提供了机会。交直流并网形成了交直流混合电网的新范式。实现这一概念的最具挑战性的配置是孤岛交直流耦合微电网，其中两个子电网都没有松弛母线，功率可以在子电网之间双向流动，分布式电源的下垂控制使系统变量依赖于负载，子电网可能过载，交流侧分布式电源可能经历不平衡负载。例如，据报道，安大略省北部一个偏远社区的交流微电网出现了高达100%的不平衡。该研究计划的长期目标是通过分析、规划、设计、模拟和实验验证，为离网的偏远社区、采矿和军事应用开发改进的、实用的基于可再生能源的混合微电网解决方案。在5年的探索资助期内，申请人和他的团队将尝试：(I)通过采用自主顺序方法来解决交、直流子电网的潮流问题，并使用基于对称分量的算法，来提高稳态分析工具的精度和计算效率；(Ii)通过互联换流器在交流侧和直流侧之间动态地分配电能，避免子电网过载和交流分布式电源的不平衡运行；(Iii)通过互联变流器与交、直流子电网的递阶控制相协调，提高递阶控制器的性能；(Iv)通过开发创新的直流微电网解决方案，加快向不享有特权的离网社区提供电力供应；以及(V)通过在混合微电网中采用混合储能系统和四象限电动汽车充电器，解决基于可再生能源的DG和负荷的高斜率问题，并促进提供辅助监管服务。该计划是通过加入电力行业和离网远程社区，将研究范围扩大到探索资助期之后，并申请一笔可观的赠款，以致力于设计和实施一个实际大小的混合微电网，该微电网在服务于社区的同时，将作为收集宝贵数据的工具。拟议的研究计划将极大地有助于为学术界和工业界培养高素质的人才，并将促进加拿大作为一个负责任地投资解决全球环境问题并改善北部偏远社区土著人民生活的国家的全球地位。

Last decade witnessed an unprecedented increase in the integration of DC-based distributed generation (DG) and loads in the grid via power electronic converters. This has created both a challenge, due to the additional losses introduced by the required DC/AC and AC/DC conversion stages, and an opportunity for efficiency enhancement through implementation of DC grids and elimination of unnecessary conversion stages. Coexistence of AC and DC grids forms a new paradigm called hybrid AC-DC grid. The most challenging configuration for realizing this concept is islanded AC-DC-coupled microgrid, where none of the two subgrids has a slack bus, power can flow between the subgrids bidirectionally, droop control of DGs makes system variables load-dependent, subgrids can get overloaded, and AC-side DGs can experience unbalanced loading. As an example, unbalances of up to 100% have been reported in AC microgrid of a remote community in Northern Ontario. The long term objective of the proposed research program is to develop improved, practical renewable-energy-based hybrid microgrid solutions for off-grid remote community, mining, and military applications, via analysis, planning, design, simulation and experimental verification. Within the 5-year Discovery Grant period, the applicant and his team will attempt to: (i) improve the accuracy and computational efficiency of steady-state analysis tools by taking an autonomous sequential approach to solving the AC and DC subgrids' power-flow problems, and using a symmetrical-component-based algorithm; (ii) avoid subgrid overloading and AC DGs' unbalanced operation by routing the power dynamically among the AC-side phases and DC-side through interlinking converters; (iii) improve performance of hierarchical controllers by coordination of hierarchical control of the interlinking converters with those of AC and DC subgrids; (iv) expedite provision of electricity access to unprivileged off-grid communities by developing innovative DC microgrid solutions; and (v) address high ramping rates of renewable-energy-based DGs and loads, and facilitate provision of ancillary regulation services, by incorporating hybrid energy storage systems and 4-quadrant EV chargers in hybrid microgrids. The plan is to expand the dimensions of research beyond Discovery Grant period by joining power industry and an off-grid remote community, and apply for a sizable grant to work towards design and implementation of an actual-size hybrid microgrid that, while serving the community, will act as a tool for collection of invaluable data. The proposed research program will contribute greatly to training of highly-qualified personnel for academia and industry and will advance global position of Canada as a country that invests responsibly to address global environmental issues and improve the lives of its indigenous people who form the remote communities of the north.