Logarithmic derivative based quantitative analysis of oscillatory stability in renewable powered systems

The electromagnetic oscillatory instability resulting from converter control interactions represents a crucial issue in large-scale renewable powered systems. Quantitatively assessing the system's oscillatory stability is of utmost importance. However, mainstream stability analysis methods documented in the literature face a challenge when it comes to quantitative identification of the dominant oscillation modes using coarse frequency-domain data. This paper introduces a novel method based on an admittance network to conduct oscillatory stability analysis by precisely identifying the frequency and damping of oscillation modes. Initially, an extended nodal admittance matrix (Extended-NAM) is developed to represent the frequency-coupled admittance network model (FCANM) of a typical renewable powered system. Subsequently, the paper proposes taking the logarithmic derivative of the determinant of the Extended-NAM to accurately identify the oscillation modes. The efficacy of the proposed logarithmic derivative-based quantitative oscillatory stability analysis method is validated on two practical renewable powered systems. The analysis results obtained demonstrate the accuracy and computational efficiency of the proposed method over other stability analysis approaches.