Transient Stability of Synchronous Condenser Co-Located With Renewable Power Plants Under High-Resistance Faults and Risk Mitigation

Abstract

Synchronous condensers (SynCons) are widely used in supporting the integration of renewable power plants (RPPs) in weak grids. However, recent research suggests that a SynCon co-located with RPPs may be prone to transient rotor angle instability due to the excessive active power injected by nearby RPPs during metallic faults. This paper further discovers that the transient stability of the SynCon may be lost even it generates electrical power during high-resistance faults. This novel mechanism of instability is investigated by deriving power-angle characteristics in different fault scenarios, and then the effect of the system parameters on the stability is analyzed via a proposed index based on the critical clearance time (CCT). It reveals that inappropriate parameters of SynCons, weak grid, and voltage support during fault ride-through (FRT) all contribute to such transient instability. To mitigate such instability, an adaptive FRT strategy is proposed. The electromagnetic transient (EMT) simulations based on the PSCAD are carried out to validate the effectiveness of the theoretical analysis and the proposed adaptive control strategy.