High performance control of harmonic instability from HVDC link system

This paper investigates the usefulness of a novel control method for a HVDC link system which suffers from a severe condition of low order harmonics. This control scheme uses the feedforward control method which is a directly controlled DC current at the DC link system. The studies of this paper are aimed at improving the dynamic response of a HVDC link system in disturbances such as faults. To achieve those objectives, digital time domain simulations are employed by the electromagnetic transient program for a DC system (EMTDC). This method results in stable recovery from faults at both rectifier and inverter terminal busbars for an inherently unstable HVDC system. It has been found to be robust and control performance has been enhanced.