Grant: Discovery Grants Program - Individual

The proliferation of inverter-interfaced distributed energy resources (DERs) has led to a paradigm shift in the behaviour of emerging power systems. In particular, the response of an inverter-dominated microgrid, which relies heavily or exclusively on inverter-interfaced DERs, to a short-circuit fault or disturbance is significantly different from that of a traditional distribution system. The lack of inertia in inverters results in excessive frequency deviations and poor dynamic response to disturbances. Among the various inverter control strategies, the virtual synchronous generator (VSG) control, which emulates virtual inertia, damping, and impedance, offers a more promising solution but introduces additional transient stability problems and protection challenges.   The long-term objective of this research program is to develop protection and control strategies that ensure the stable, reliable, and secure operation of the next generation alternating-current (AC), direct-current (DC), and hybrid AC-DC microgrids. In the short term, this research program will focus on VSG-based AC microgrids with the following objectives: 1) Improving VSG stability and dynamic behaviour: The transient stability of the VSG is highly affected by its virtual reactance. An adaptive virtual reactance-based algorithm will be devised to enhance the VSG transient stability, whenever needed. Furthermore, a robust damping controller will be developed to mitigate power oscillations caused by the interaction of VSGs. 2) Protecting the VSG-based microgrid against faults: To enable reliable protection of the VSG-based microgrid, this research will develop a directional fault detection element and a high-impedance fault detection algorithm, considering the impacts of the inverter current limit and the virtual impedance. 3) Protecting the integrity of the VSG-based microgrid: Adaptive virtual inertia, damping, and impedance can be utilized to improve the dynamic behaviour of individual VSGs. However, uncoordinated variations of these parameters may worsen the dynamics of the islanded microgrid. A mechanism will be devised to manage and optimize the allocation of VSG virtual parameters considering microgrid stability constraints. Additionally, a robust load shedding strategy will be developed to protect the integrity of the VSG-based microgrid under variations of virtual parameters.    The novel strategies and cost-effective technologies that are expected to be developed by this research program will facilitate the grid integration of renewable energy sources and improve the dynamic behaviour, stability, and resiliency of microgrids that supply energy to critical infrastructures, remote communities, and sensitive consumers. The results will pave the way for Canada's transition towards reaching net-zero emissions and also reduce the adverse effects of outages caused by natural disasters, equipment failures, and faults on the Canadian economy and well-being of Canadians.