Security constrained optimal power flow for HVAC and HVDC grids

This paper includes security constraints in OPF calculations for combined HVAC and HVDC grids. Two formulations of the problem are considered: a preventive and a corrective formulation. The outages of lines, generators and terminal stations are included. The preventive control method assumes that no control actions are taken after a contingency happens, meaning that all actions must be performed in advance. Linear sensitivity factors are used to calculate the influence of the contingency. Under the corrective control method, control actions can be performed both before and after a contingency, using fast controllable HVDC terminals. The two methods are applied to the IEEE14 and the RTS96 test cases, both expanded with an HVDC grid. The corrective control is computationally more intensive, but, in general, gives more economical results.