Cyber-attack-induced equilibria of high-voltage direct-current power transmission systems

The electric power system is the largest man-made autonomous intelligent machine, which is of vital importance but vulnerable to cyber threats. This study investigates cyber-attack-induced equilibria, i.e., steady-state operation points, of two-terminal high-voltage direct-current (HVDC) power transmission systems, which play a critical role in maintaining power balances. By analytically mapping the control curves of two HVDC converters onto a common control plane, we show that originally linear characteristics become quadratic or more complex. Then, we derive propositions characterizing attack-induced switching of HVDC control strategies as well as the consequent shift of HVDC equilibrium points. Time-domain MATLAB/Simulink case studies validate the theoretical results, highlighting abrupt bulk power reversals and bifurcation-like behaviors under small measurement perturbations. The proposed framework provides HVDC system operators with explicit tools to assess and mitigate attack-driven HVDC operating risks.