August 2022
I am sincerely grateful to the many wonderful colleagues at the UNIFI consortium for having me present my older work on methods to emulate inertia and perform frequency control with wind and photovoltaic generators. My seminar is scheduled on Monday Sep. 19th at 4 pm ET, as part of the Fall 2022 Seminar Series (more information here).
The UNIFI project aims to conduct advanced research, design testing and develop standards on grid-forming inverters. Inverters are the power electronics devices that enable the efficient connection of many renewables to the electrical grids. With the gradual replacement of conventional units by renewables, the roles of the former pass on to the latter. “Grid-forming” is the functionality necessary to establish and maintain a standardized three-phase alternating current that serves some load demand. Inverters have been typically able to perform “grid-forming” at limited off-grid scales, but are now expected to expand it at the level of large interconnected grids.
In my seminar I will focus mostly on the side of the sources, specifically wind and photovoltaic energy. Traditionally, these generators have been operated on strategies of maximum power absorption. Even though these strategies optimize the use of renewable sources, they are inflexible when load demand varies or the generation from other resources fluctuates. In fact, due to electricity physics any generation-demand imbalance, reflects to changes in the electrical frequency of the alternating currents; this change of frequency can control generators to respond to the load-generation imbalances. With wind and photovoltaic generators at maximum power absorption, responding to frequency signals that requires them to contribute additional power is impossible; hence, the requirement to procure reserves arises. I will review the methods, challenges, some results of real-world testing and expand on how grid-forming functionalities might be affected by inertia emulation and frequency control by wind and photovoltaic units.