Unconventional HVDC Control Technique for Stabilization of a Weak Power System

A Constant Reactive Current Control (CRC) technique [1] was implemented in a fundamental frequency digital simulation. The interaction between the HVDC link and the associated AC system was analyzed and compared to the conventional current margin control method, for a very weak inverter AC system. The system studied has shown an unstable behaviour when the conventional method was used. By changing the control technique to the CRC method, system performance was significantly improved. It was also shown that with the CRC philosophy, a current modulation signal could be introduced without any harm to AC voltage stability. The CRC technique was also compared to a combined modulation-voltage and current-in a conventional control scheme, and showed a superior general behaviour.