An Approach for Assigning Responsibilities of Short-Term Voltage Variations in Electrical Power Systems

Short-term voltage variations (STVVs) are phenomena manifested as voltage sags, voltage swells, or interruptions lasting up to 1 minute. Despite their short duration, they greatly influence the operations of loads. In fact, residential, commercial, and industrial consumers can be strongly affected when facing supply discontinuities, loss of production, physical damages, and other issues. Under such circumstances, conflicts may arise between suppliers and consumers. Thus, a strategy that identifies whether the STVV phenomenon was produced upstream or downstream of a given point of common coupling between two agents interconnected by a transformer is proposed in this paper. The methodology is based on the transference mechanism of imbalance indicators through this connecting transformer. The current process is not about determining the physical location of the disturbance in the network but only about establishing the responsibility for the disturbance. The effectiveness of the process is determined through computational and experimental studies, for which typical electrical systems are employed. To this end, unbalanced STVVs are imposed on these systems, and the voltage and current imbalance levels on the primary and secondary sides of transformers are correlated to validate the proposal.