Black-Box Impedance-Based Stability Assessment of Dynamic Interactions Between Converters and Grid

Abstract

This paper proposes an impedance/admittance-based methodology for stability assessment of converter-based device connections to power systems. The proposed methodology is designed to model the dynamics of detailed black-box converter models, derived from impedance frequency response measurements. From the converter’s impedance frequency response measurements, a linear time-invariant (LTI) representation of its dynamics is obtained in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> domain using a vector fitting technique. This representation is incorporated in the state-space representation of the whole power system in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> domain, which is used to perform stability assessment considering traditional eigenvalue analysis and participation factors computation. The proposed methodology is tested in the 39 Bus New England system, including detailed models of a VSC windfarm and a modular multilevel converter (MMC) technology-based STATCOM. It has been found that the proposed impedance-based methodology is able to accurately predict the dynamic performance of black-box converter models, unstable operating conditions and converter control interactions between devices.