Method of Determination of Voltage Dip Source Location in Relation to the Border of Balance Responsibility

The uncertainty of voltage dips source location on the border of balance responsibility complicates the timely response of maintenance personnel to faults in the electrical network and also leads to frequent legal disputes between electricity consumers and suppliers. The determination of the fault direction—towards the consumer or the electricity supplier—is carried out by analyzing the negative-sequence voltage on the power line and the negative-sequence current flowing through that line, followed by comparing their relative phase angles. It is important to note that the angular characteristics of voltage dips within an internal network (e.g., within a facility) may significantly differ from those in external networks due to the heterogeneity of networks with different nominal voltage levels. This can affect the angular characteristics and lead to substantial errors. Research also shows that determining torque for the conventional negative-sequence directional element has several limitations: the negative-sequence voltage is inversely proportional to the source power; the fault impedance reduces the level of the negative-sequence current; and the values of the traditional directional torque directly depend on the magnitude of the negative-sequence voltage and current, which limits the ability to accurately determine the fault direction. This work presents the method for identifying the location of a voltage dip relative to the boundary of balance responsibility in a three-phase electrical network by developing a directional element based on the total negative-sequence impedance. In this approach, the total negative-sequence impedance is always negative for forward faults and always positive for reverse faults. The effectiveness of this method for fault direction detection was verified through simulation of a type B voltage dip. The results of the simulation demonstrated acceptable accuracy.