CALCULATION METHOD FOR THE CONTRIBUTION OF HVDC STATIONS WITH LINE-COMMUTATED CONVERTES (LCC) TO THE AC SHORT-CIRCUIT CURRENT

Short-circuit currents are a key measure for the planning of AC high voltage electrical networks. In this paper, the short-circuit current contribution of a HVDC system with line-commutated converters (LCC) to the short-circuit current in the AC system is investigated. Based on simulations in PSCAD/EMTDC the influence of different factors on the short-circuit current contribution is studied. These factors include the rating of the HVDC system, its operating point, different DC links such as back-to-back links, cables and overhead lines with varying DC line lengths and the type of short circuit and its distance from the HVDC converters. Based on the findings relevant factors are identified. On the basis of the simulation results a simplified analytical approximation for the short-circuit current contribution is derived, which takes into account the identified relevant factors.