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

在过去的十年里，基于直流的分布式发电（DG）和负载通过电力电子变换器集成在电网中的比例空前增加。由于所需的DC/AC和AC/DC转换级引入的额外损耗，这既产生了挑战，又产生了通过实现DC电网和消除不必要的转换级来提高效率的机会。交直流电网的共存形成了一种称为交直流混合电网的新模式。实现这一概念的最具挑战性的配置是孤岛AC-DC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，DG的下垂控制使系统变量依赖于负载，子电网可以过载，并且AC侧DG可以经历不平衡负载。作为示例，在北方安大略的偏远社区的AC微电网中已经报告了高达100%的不平衡。拟议研究计划的长期目标是通过分析，规划，设计，仿真和实验验证，为离网远程社区，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年的发现资助期内，申请人及其团队将尝试：（i）通过采用自主顺序方法解决AC和DC子电网的潮流问题，并使用基于元件的算法，提高稳态分析工具的准确性和计算效率;（ii）通过互连转换器在AC侧相和DC侧之间动态地路由功率，避免次电网过载和AC DG的不平衡操作;（iii）通过协调互连转换器的分级控制与AC和DC子电网的分级控制来提高分级控制器的性能;（iv）通过开发创新的DC微电网解决方案来加快向无特权的离网社区提供电力接入;以及（v）通过在混合微电网中纳入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和负荷的高斜坡率，并促进辅助调节服务的提供。该计划将通过加入电力行业和离网远程社区来扩大研究范围，并申请一笔可观的赠款，用于设计和实施实际规模的混合微电网，该混合微电网在为社区服务的同时，将作为收集宝贵数据的工具。拟议的研究计划将大大有助于为学术界和工业界培训高素质的人才，并将提高加拿大作为一个负责任地投资解决全球环境问题和改善其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.