Virtual Synchronous Condenser Control Strategy for Enhancing Transient Voltage Support During Grid Faults and Recovery

Synchronous condensers (SCs) are widely recognized for their superior dynamic reactive power support capability. However, their large-scale deployment in distributed power systems with high renewable energy penetration is constrained by high capital costs and maintenance complexity. To address this limitation, a virtual SC control strategy is proposed for grid-connected renewable energy inverters. The method enables these inverters to emulate the field-forcing characteristics of SCs, thereby providing effective transient voltage support at the point of common coupling (PCC) during the fault recovery period phase, while simultaneously suppressing transient overvoltage at the onset of recovery. A mathematical model capturing the internal electromotive force (EMF) dynamics of SCs is developed, and practical control laws are derived for direct implementation in inverters. Through phasor-domain analysis, the transient voltage support capability is analytically characterized, and the physical significance of key control parameters is elucidated. Experimental validation under various grid fault scenarios is conducted, confirming the effectiveness and safety of the proposed strategy.