To enhance the leading-phase operation depth and overvoltage suppression capability of synchronous condensers

this paper systematically investigates the small-signal stability of dual-excited synchronous condensers under deep leading-phase operation conditions with different q-axis control modes and proposes corresponding control strategies and implementation methods. Firstly

a comprehensive small-signal analysis model incorporating the sixth-order state-space equations of dual-excited machines and d-q axis control functions is established

along with its characteristic matrix. Secondly

eigenvalue analysis is employed to systematically examine the influence of various q-axis control modes on the distribution patterns of dominant eigenvalues in the small-signal under deep leading-phase operating conditions. Finally

the rotor excitation voltage control equations under coordinated d-q axis excitation conditions are derived

culminating in the design of an excitation controller with superior engineering applicability. Simulation results demonstrate that the proposed excitation control strategy and implementation methodology can effectively ensure dynamic stability during deep leading-phase operation and improve the short-term leading-phase ability of the synchronous condenser to a level far beyond its apparent capacity.