A direct power control for Hybrid HVDC transmission systems

In this paper, a model-based Direct Power Controller (DPC) is proposed for Hybrid HVDC. This Hybrid comprises a Voltage Source converter (VSC) using in the sending side and Line-commutated Converter (LCC) using in the receiving side. This application is potentially attractive for power flow in one direction, for example the integration of offshore wind farms. DPC controller is able to control directly the instantaneous power and reactive power in the VSC side. In addition the DPC includes an adaptation mechanism to cope with uncertain parameters. The LCC maintains the DC voltage using a proportional-integral (PI) controller. PSCAD/EMTDC simulations are provided to illustrate the performance of the proposed controller at start-up, at steady state and the transition when there is change of power reference.