Stability Analysis of Real-World Subsynchronous Oscillations via Black-Box EMT Models

In this paper, we demonstrate methods to extract <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> admittance for a solar photovoltaic (PV) farm from its black-box model used for electromagnetic transient (EMT) simulation. Each <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> admittance corresponds to a certain operating condition. Based on 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> admittance, analysis is carried out to evaluate how grid strength and solar irradiance may influence stability. Two types of stability analysis methods (open-loop system based and closed-loop system based) are examined and both can deal with <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> admittance's frequency-domain measurements directly and produce graphics for stability analysis. The findings based on <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> admittance-based analysis are shown to corroborate EMT simulation results.