Short-circuit Calculation in AC Networks in Case of HVDC Stations with Line-commutated Converters (LCC)

Short-circuit currents are a key measure for the planning of AC high voltage electrical networks. These currents can be calculated according to the IEC standard 60909-0: 02-2016. However, the existing standard does not consider the contribution of HVDC stations. In this paper, the short-circuit contribution of a HVDC system with line-commutated converters (LCC) is investigated and an analytic expression for the short-circuit contribution is proposed for the usage in an updated version of this standard. For that, the single contributions of the LCC HVDC system's parts are examined and the processes are studied taking place during an AC short circuit. With this knowledge, an analytic approximation can be derived and is verified by simulations in EMTDC/PSCAD.