Improved DR and CBM methods for finding relative location of voltage sag source at the PCC of distributed energy resources

Abstract

The presence of distributed energy resources (DERs) such as inverter based distributed generations (IBDGs) in active distribution systems has a significant effect on the location of voltage sag sources. And so it is essential that traditional methodologies for voltage sag source location be extensively investigated. From the viewpoint of the owner of the IBDG, it is important to know whether the source of the voltage sag is within its power system or not. This paper investigates the impact of fault response of IBDGs on main methods for relative location of voltage sag sources. The results show that many of the methods are not applicable for voltage sag source location in monitors at the PCC of IBDG to grid and are only usable in monitors close to synchronous based distributed generations (SBDGs). Therefore, two new methodologies are introduced: Improved distance relay (IDR) and Improved current based method (ICBM). These methodologies are based on the previous DR and CBM methods, and use the threshold and saturation currents of the inverter of IBDG and the positive sequence power factor. The new methods are evaluated by applying numerical simulations. The obtained results show that the proposed methods applied to monitors installed at the PCC of an IBDG in active distribution systems are very accurate.