A new analytical expression for OLTC tap positioning: The Bus Injection Tap Setting approach

Abstract

As transition to green and sustainable electricity distribution networks, the new-tech energy system integration is expanding rapidly. This transformation in distribution networks brings with it more frequent voltage violation occurrences. Among conventional measures for distribution-level voltage regulation such as OLTC tap changes, shunt capacitor switching, and line voltage regulators this paper concentrates on OLTC tap adjustment. This paper presents methodology for the tap setting with a new analytical expression named as Bus Injection Tap Setting. It is based on bus current injection consisting of bus load and voltage. It is formed by obtaining the bus voltage in terms of the voltage setting of the on-load tap changer placed on the swing bus. Regardless of the distribution network size or operating condition, the proposed methodology provides accurate tap adjustment to eliminate voltage violations with the same application procedure and minimal tap movement. As a simulation study, this method is tested for low-voltage and high-voltage violation cases in a 33 bus test system, and for all cases, it gives the accurate tap setting, tap constraint compliance, and voltage violation elimination. Finally, the proposed expressions significantly reduce the computational burden compared to the optimization based approaches, and there is low data necessity to implement, requiring only two power flow analyses for all distribution networks and cases. © 2025 Elsevier B.V., All rights reserved.