This paper proposes a decentralized, passivity-based cont rol design for power stations in a multi-terminal High Voltage Direct Current transmissi on system. The control algorithm is shown to asymptotically stabilize the closed-loop syste m when the voltage set points are appropriately selected. The analysis is carried out taking into account actual power, current and voltage saturations that affect power stations and, consequ ently, the control action. Numerical results illustrate the performance of the obtained control lers.