Multi-Infeed HVDC with UPFC as Ancillary Controller

This paper evaluates critically the operational aspects of multi-infeed HVDC network during various conditions such as ESCR variation and faults at any one of the remote converter terminals. The study reveals that FACTS controllers may significantly improve operational reliability under dynamical changes. It has been demonstrated through extensive simulation studies that voltage and power in the multi-infeed network is regulated effectively with Unified Power Flow Controller (UPFC). During course of investigation, this has been found that an appropriate integration of a tuned UPFC in multi-infeed network greatly helps not only to optimize the power flow in the AC transmission lines maintaining voltage and power stability during sudden loss of generator or fault in the network but also assists in smooth multi-infeed converter operation with least excursions on converter controls. A sample multi-infeed HVDC network with UPFC is modelled in PSCAD/EMTDC environment and the simulation results demonstrate significant contribution of UPFC controller for effective oscillation damping even in weak AC system conditions and also recovery after fault is cleared.