The transient performance of High Voltage Direct Current (HVdc) power transmission systems depends heavily on the current regulators associated to the converter control systems. The tuning of these current regulators is a function of the converters short-circuit ratio, or equivalently of all the net converter commutation resistances. These resistances vary with the network operating conditions and they are affected by AC system contingencies. This paper concerns the adaptive tuning of the critical converter control system parameters in function of an estimate of the net commutation resistances. Compared to regulators with constant gains, the proposed control and estimation algorithms improve the dc system dynamic response. This is demonstrated by a computer simulation of a typical HVdc system.