Grid Strengthening IBR: An Inverter-Based Resource Enhanced by a Co-Located Synchronous Condenser for High Overcurrent Capability

Abstract

With the increasing penetration of inverter-based resources (IBRs) and the standing down of synchronous generator-based resources (SGBRs), some IBRs, at least, need to provide grid support functions commonly provided by SGBRs. IBRs usually have a much smaller overcurrent capability than SGBRs, which can result in weak grid strength and corresponding issues on grid transient voltage support, system protection, and black start. This paper aims at addressing the low overcurrent capability issue of IBRs from the source side by combining an IBR with a co-located synchronous condenser (SC). Dubbed grid strengthening IBR (GSI), the proposed setup in grid forming mode uses the SC to regulate the terminal voltage and the IBR to regulate the frequency. The proposed GSI is evaluated through its comparison with an SGBR in the single-unit operation considering different grid faults, multi-unit operation, and transient stability performance. It is verified that the GSI can provide an overcurrent and maintain the terminal voltage comparable to or even slightly better than the SGBR during grid faults. The GSI does not have any transient stability issues; even after a long fault period, it can reestablish the system synchronism. The GSI can help the penetration of the IBRs in the system, as the system operation and the system loads will be largely unaffected, even during transients.