Small scale multi-terminal HVDC transmission test rig

This paper describes the development of a simple experimental rig for a three-terminal HVDC transmission system that was designed with voltage source converters (VSC) for onshore wind farms. Two wind power plants (WPPs) were interconnected and directly connected to the inland grid through a 12V 1.44W DC link. A Master-Slave control arrangement was considered and partially implemented to maintain voltage of the DC link and inland grid. A double inputs-single output configuration was considered due to its small scale design. The design of the rig was also modelled for real life situations using MATLAB/Simulink. The results obtained showed that DC link voltage steady state was reached with a slight delay and with minimum overshoot, under purely resistive load, while, on the other hand, an appreciable overshoot would be experienced under inductive loads, though steady state was quickly reached.