Improvement of Reactive Power Consumption Ability for Dual-Excited Synchronous Condenser

The traditional synchronous condenser (TSC) has strong reactive power delivery ability, however its reactive power consumption ability is restricted by the minimum field current of zero. The dual-excited synchronous condenser (DESC) has the wider range of reactive power regulation due to the two field windings on the rotor, and thus it is helpful to suppress the system overvoltage. In this paper, it is proposed a voltage and speed tracking excitation control (VSTEC) strategy which can realize the d-axis negative excitation through the feedback of the terminal voltage and avoid out of step through the feedback of the rotor speed. The control parameters of the VSTEC are calculated by the fuzzy control method. With the sudden rise of the system voltage as an example, the effect of q-axis excitation on the stability of DESC under the d-axis negative excitation mode, and the reactive power consumption ability of the TSC and DESC are calculated and compared. Further, the variations of the transient characteristic for the DESC along with the field resistance and rotor slot wedge material are revealed. The results can provide technical support for suppressing the system transient overvoltage.