System stability analysis of Xiamen bipolar MMC-HVDC project

This paper presents the controller hardware-in-loop (CHIL) testing of Xiamen bipolar MMC-HVdc project based on Real Time Digital Simulator (RTDS). It revealed the system instability of MMC-HVdc converter and its controllers for the first time. The CHIL tests show that, the small signal stability of Xiamen bipolar MMC-HVdc project is related to the system controller and circulating current suppression controller (CCSC). Also the parameters of smoothing reactors and transmission line have a great impact on the system stability. The CHIL testing and RTDS simulation results prove these findings, which are essential to the real project control and protection system designing.