Reduction of Short-Circuit Level of EHV Substation

Abstract

With the expansion of network, there is inclusion of new power stations and transmission lines in the network as a consequence of which the short-circuit levels at some of the substation increase apart from its design limit. This short-circuit current causes offensive electrodynamic force, thermal and mechanical stress and devastation to equipments. Hence, the contraction and regulation of this short-circuit current are crucial. To diminish this short-circuit current, one of the pragmatic solutions is to update the equipments so that the predicted fault current is inmost equipment capacity. This generally suggests the entire reconstruction of substation. However, this solution is very expensive. All the switchgear equipments are rehabilitated and certified ahead of upgrading the existing substations, which is quite problematic process. There are few techniques accessible for reduction of short-circuit level, namely application of high-impedance transformer, disconnection of some lines from the critical substation, bus bar splitting technique, current limiting reactor, etc. This paper discusses simulation of case study with current limiting reactor (CLR) technique and bus bar splitting technique in the substation and identifies the optimum solutions to control and reduce of short-circuit levels of EHV Substation.