Frequency domain based control design for an HVdc converter connected to a weak ac network

A small-signal frequency domain model of an HVDC system connected to a weak AC network is used for an operating point-based rectifier direct current control design. The frequency response of the open-loop system is systematically shaped, clearly showing the controller design tradeoffs involved in achieving the objectives of damped system oscillations and disturbance rejection. The performance of the controller is verified by time-domain simulation of the CIGRE Benchmark HVDC test system. This validates the use of small-signal frequency response models for HVDC system control analysis and design. The further developments necessary for a practical controller for large signal excursions are discussed.