New Impedance Method Ensures Stability for Interconnected Offshore Wind Clusters

A team of researchers led by Germano Rugendo Mugambi from DTU has published a new methodology for impedance-based stability margin analysis tailored to interconnected offshore wind clusters. As offshore grid architectures evolve, power park modules (PPMs) such as offshore wind power plants (OWPPs) are increasingly interconnected offshore. Existing stability assessments using impedance-based methods often rely on Nyquist encirclements without explicitly quantifying stability margins. This paper addresses that gap by proposing a general framework that evaluates how integrating a new OWPP affects the stability margins of an existing one at the point of common coupling. The methodology also derives a maximum allowable impedance for the new connection, ensuring compliance with minimum stability margin requirements set by system operators. Additionally, the authors introduce new Nyquist-based stability regions that provide analytical indications of margin compliance and headroom, complementing the standard generalized Nyquist criterion.

The proposed approach is validated through case studies using vendor-based frequency-domain models of two interconnected OWPPs and an HVDC system. This practical validation demonstrates the method's applicability to real-world offshore wind clusters. For grid operators and renewable energy developers, the methodology offers a clear, quantitative tool to safely expand offshore wind capacity without risking small-signal instability. By explicitly defining stability margins and allowable impedance boundaries, this work supports the reliable integration of large-scale offshore wind into existing power systems, a critical step toward decarbonization goals.