Research on Asynchronous Operation Capability and Rotor Temperature Field of Dual-excited Synchronous Condenser

With the continuous increase in the share of renewable energy, the voltage and frequency stability of power systems face significant challenges. Dual-excitation synchronous condensers (DESCs) can provide reactive power and inertia support to the grid, but their capability is affected by rotor damping. Taking a 50Mvar DESC as an example, this paper first analyzes the asynchronous operation mechanism of a DESC, considering the damping effect, and reveals the impact of damping on the stability of DESC asynchronous operation. Subsequently, it investigates the variation patterns of rotor eddy current losses and excitation winding induced voltages under different slip ratios. Following this, a local fluid-thermal coupling model for the DESC rotor is established. Based on a coupled fluid network-flow-thermal field method, the correlation between slip ratio and the temperature of rotor components is clarified. Using the maximum rotor temperature as the limiting factor, the critical slip ratio and permissible transient operating duration for the DESC are determined. The conclusions drawn can provide references for the structural design and optimization of damping in dual-excitation synchronous condensers.