Research on Low-voltage Starting Strategy of Synchronous Condensers

To reduce the high system cost associated with using high-voltage inverters for starting high-voltage synchronous condensers, this paper proposes a startup method based on a low-voltage inverter. The method introduces a twelve-pulse rectifier on the drive side, which effectively suppresses low-order harmonics and eliminates the need to modify the thyristor triggering scheme of the excitation system. This enables accurate extraction of rotor position signals from the back electromotive force (back-EMF), significantly improving startup torque while reducing torque ripple. Additionally, a closed-loop, back-EMF-based sensorless strategy is implemented to achieve full-speed-range estimation of the motor rotor position, applicable to synchronous condenser systems. Simulation studies conducted on a synchronous condenser drive simulation platform validate the effectiveness of the proposed approach. The results demonstrate smooth and reliable startup performance. This method not only enhances sensorless startup performance but also provides a practical and cost-effective solution for large-scale high-voltage synchronous motor applications, making it particularly suitable for grid-connected reactive power compensation scenarios.