Distributed multi-agent control for combined AC/DC grids with wind power plant clusters

Abstract

The combined AC/DC grids have, due to their technological features of high voltage and large capacity as well as operating flexibility and reliability, become one of the most potential solutions to connect large-scale wind farms to power systems. The traditional centralised control lacks flexibility and robustness. In contrast, the distributed control is unable to simultaneously consider global optimum and response speed. A scheme of intelligent distributed control for combined AC/DC grids is proposed to constitute a multi-agent system by equipping each terminal with an agent. While adopting the proposed control method, the optimisation of the upper layer is similar to the traditional grid dispatch and the lower layer system achieves the group compromise through the interaction and coordination among the agents and between the agents and the system. Based on the state information such as the voltage and the frequency of the neighbouring converter stations, the combined AC/DC grids can allocate the active power reasonably through the consistency control and provide the frequency support of the AC grid. Finally, four operating scenarios, including wind speed jump, wind power plant cluster disconnection, converter station failure and load demand response, are verified in a typical model of combined AC/DC grids by using the PSCAD/EMTDC software.