A comprehensive power quality assessment of an urban low-voltage distribution network in Lubumbashi, Democratic Republic of the Congo, reveals critical compliance failures with international standards. Conducted from October 2024 to February 2025, the study monitored five radial feeders supplied by the Babemba medium-voltage/low-voltage substation using Class B power quality measurement equipment.
The investigation documented persistent voltage degradation as the primary disturbance. Chronic under-voltage conditions prevailed, with typical deviations ranging from −20% to −30% below nominal levels, and voltage dips reaching 70–80% during peak loading. System reliability metrics showed a System Average Interruption Frequency Index of 7.85 events annually and a System Average Interruption Duration Index of 491 minutes per year. One medium-voltage outage lasted approximately 48 hours, demonstrating limited distribution system resilience.
Secondary power quality disturbances included significant phase voltage imbalance reaching 18%, neutral currents exceeding 327 amperes—indicating unbalanced loading and potential safety hazards—and short-term flicker values approaching 1.5, above recommended comfort thresholds for sensitive equipment operation.
The research attributed observed disturbances to multiple factors: heterogeneous feeder loading patterns, suboptimal network configuration, non-standard electrical connections, and documented physical deterioration of aging infrastructure. These interconnected problems are typical in rapidly urbanizing African distribution networks where rapid demand growth outpaces planned infrastructure expansion and maintenance investment.
The study provides quantitative evidence supporting prioritized network interventions including feeder reinforcement, phase rebalancing measures, infrastructure rehabilitation, and implementation of permanent local power quality monitoring systems. These findings establish a practical baseline for utilities and regulators planning distribution network upgrades and offer comparative data for similar urban networks across sub-Saharan Africa facing comparable power quality challenges.
