A Methodology for Impedance-based Stability Margin Analysis for Interconnected Offshore Wind Clusters
For system operators and engineers integrating offshore wind power plants, this work provides a practical tool to quantify stability margins and ensure compliance with requirements, addressing a gap in existing impedance-based methods.
This paper proposes an impedance-based methodology to evaluate stability margins of interconnected offshore wind clusters and derive maximum allowable impedance for new connections to meet operator-specified margins. The method is validated using vendor-based models of two offshore wind power plants and an HVDC system.
With recent developments in offshore grid architectures, power park modules (PPMs) such as clusters of offshore wind power plants (OWPPs) are increasingly interconnected offshore. Consequently, it is necessary to assess how integrating a new OWPP affects the stability margins of an existing OWPP at the point of connection. Although impedance-based methods are widely used for small-signal stability assessment of interconnected converter-based systems, many studies rely primarily on Nyquist encirclements and do not explicitly quantify stability margins. Thus, this paper proposes a general impedance-based methodology to (i) evaluate the stability margins of an existing connection after a new PPM is integrated and (ii) derive a maximum allowable impedance for the new connection such that the minimum stability margin requirements specified by system operators are satisfied and stable operation is maintained. In addition, new Nyquist-based stability regions are introduced to complement the generalized Nyquist criterion, providing analytical indications of margin compliance and headroom. The proposed method is validated through case studies using vendor-based frequency-domain models of two interconnected OWPPs and HVDC system.