Extended Nodal Admittance Matrix Based Stability Analysis of HVDC Connected AC Grids

Motivated by emerging oscillation issues of high-voltage direct-current (HVDC) transmission system resulted from the interaction with AC grids, impedance-based stability analysis becomes an attractive approach in de-risking studies due to capability black-box modelling and clear physical meaning. However, assessment HVDC is typically conducted either side or DC side, without fully considering both grid dynamics, thus impairs evaluation accuracy. In this paper, nodal admittance matrix based resonance mode method extended include dynamics through formulating a hybrid AC-DC matrix. To achieve goal, interfacing-converters are modelled as three-port networks one port two ports (in dq-frame) integrating frequency coupling dynamic coupling. contrast widely adopted Nyquist-based methods, proposed does not requires knowing number right half-plane poles minor-loop gain, simplifies analysis, moreover, participation factors nodes critical modes can be identified eigenvalue-decomposition which favor design mitigation measures. The effectiveness validated EMT-simulations MATLAB/Simulink.