Comparison Between Voltage Droop and Voltage Margin Controllers for MTDC Systems

This paper studies the problem of DC voltage control in a HVDC multi-terminal system based on voltage source converters. The control scheme used is based on inner current and outer loops. External loops define or modify the power reference in each converter. Master- slave DC voltage, droop voltage and margin voltage controllers are described, and their implementation diagrams are depicted. Dynamic behaviour of the MTDC grid equipped within DC voltage controllers is studied and analysed. A three terminal MTDC system subject to converter loss is simulated. Margin and droop DC voltage controllers are tested, indicating relevant differences in the use of both controllers.