A robust co-ordinated control scheme for HVDC transmission with parallel AC systems

This paper introduces a practical control philosophy for HVDC transmission in parallel operation to an AC system with particular emphasis on coordination of both transient and dynamic stability. Systematic development of the control scheme on the basis of on-line identification, optimal control and rule-based bang-optimal co-ordination principles is presented. Verification tests of the scheme on a physical HVDC/AC system simulator show that the simple control computer algorithm is practical and robust. The controller can successfully distinguish between different system fault severities and adapts its output signals to provide maximum synchronising torque and ensure optimal damping of power oscillations