A Generalized N Terminal Current Order Control Scheme for LCC MTDC

This research work proposes a current order sharing technique for LCC MTDC power system. LCC MTDC architecture has great advantages over other HVDC transmission technologies because of its huge power handling capability, simple design and less initial and maintenance cost. Simple two terminal HVDC technology have evolved so much but the MTDC technology still have some outstanding problems which need to be addressed. Current order sharing between MTDC terminals plays an important role in stable DC transmission and lack of suitable current order sharing causes DC voltage collapse or current saturation problems for terminals. A dynamic current order sharing technique is developed for LCC MTDC system in which terminal current order is being calculated based on current ratio of respective terminal to total current. The technique has ability to readjust current order for each terminal in case of any disturbance. A generalized nrec × ninv terminals current order calculation method is also proposed for MTDC system. The method is investigated under fault conditions in PSCAD to check its feasibility. The results prove that the proposed technique self-adjusts current order as the fault is cleared or any terminal has lost operation.