Influence of Distributed Generation on Voltage Performance of the Enugu Electricity Distribution System

Abstract

Voltage regulation remains a persistent operational challenge in many Nigerian radial distribution networks due to long feeder lengths, high resistance-to-reactance ratios, and increasing load demand. This study investigates the influence of hybrid Distributed Generation (DG) on the voltage performance of a representative 11 kV feeder within the Enugu Electricity Distribution System (EEDS). A detailed network model comprising 47 load buses was developed and analysed using load flow simulation in ETAP. Two operating scenarios were examined: a base case without DG and a DG-integrated case incorporating synchronous generators, solar photovoltaic (PV) systems, and battery energy storage units. Base case results revealed widespread marginal under-voltage conditions, with a minimum bus voltage of 10.601 kV (96.37% of nominal), indicating systemic voltage depression along the radial feeder. Following DG integration, the minimum voltage improved to 10.685 kV (97.14% of nominal), representing an overall voltage enhancement of approximately 0.79%. The improvement was uniformly distributed across the feeder, confirming that hybrid DG primarily reduces feeder current magnitude and associated line voltage drops. No over-voltage violations were observed, demonstrating that moderate DG penetration can enhance voltage regulation without compromising statutory limits. The findings confirm that hybrid distributed generation provides measurable and technically meaningful voltage support in weak radial distribution systems such as EEDS. However, full restoration to nominal voltage levels requires coordinated reactive power control or higher penetration at the medium-voltage level. The study provides practical planning insights for distribution utilities seeking to integrate DG as a voltage support strategy in developing power systems.