Improved power control bandwidth of grid-forming sources in a CERTS microgrid

Abstract

Grid-forming sources allow islanded operation of microgrids by providing closed-loop regulation of the microgrid voltage and frequency. Dynamic control of the voltage magnitude and frequency around their rated values provides the means for balancing the reactive power and real power using CERTS droop algorithms. Power-regulating algorithms are also applied to constrain operation within the power limits of each source, but the power regulation bandwidths are typically low because of low system damping. The limitations to increasing the power regulation bandwidth are derived, and two methods for increasing the bandwidth are introduced using either active damping or loop-shaping techniques. A combination of analysis and experimental verification are used to demonstrate the effectiveness of these techniques for raising the power control gains in order to increase the power regulation bandwidth without degrading microgrid stability.

Research Roadmap on Grid-Forming Inverters

“…Recent advances in voltage control for inverter systems are mostly concentrated in microgrid systems with droop control (Lasseter and Piagi 2004) and/or off-grid applications. With respect to primary-level volt-VAR control, virtual impedances have been used to assist with reactive power sharing and to mitigate parameter sensitivity (Erickson, Jahns, and Lasseter 2012;Guerrero 2011;Mahmood, Michaelson, and Jiang 2015). To further enhance reactive power sharing and reduce steady-state errors, communications-based secondary-level controllers have been proposed (Simpson-Porco et al 2015;Guerrero et al 2011).…”

V2G integration and experimental demonstration on a lab-scale microgrid

“…The proportional gain provides the droop control dynamic characteristics which are shared among the rest of the sources in the CERTS microgrid, and are studied elsewhere [15]. The integral gain minimizes the error ܲ − ܲ , ensuring that, in the long term, the V2G charger will charge the vehicle at the desired power rate ܲ .…”

Grid-Forming Converters for Stability Issues in Future Power Grids

“…Its functionality can be added to GFL inverters too. So, GFM converters can perform better and provide voltage support in weak inertial grids [61]. The importance of voltage control or stability is enhanced for the developing DC grids.…”