Assessing the technical readiness of Ghana's distribution grid for electric vehicle integration: A case study revealing transformer overload and harmonic violations

The rapid electrification of transportation in Ghana, with projections of 500,000 electric vehicles (EVs) by 2030, presents significant technical challenges for the country’s aging urban distribution infrastructure. This study evaluated the technical readiness and preparedness of the Maase distribution network in the Ashanti Region under peak conditions to support Level 3 (150 kW) EV charging penetration, utilizing DIgSILENT PowerFactory 2021. Baseline simulations under peak loading reveal critical violations, indicating 42% of transformers are overloaded, operating between 85.6% and 189.5% of their rated capacity without EV integration, and some exceeding 300% loading with penetration of EVs, which signifies critical stress. To address these limitations, the study models infrastructure upgrades such as transformer resizing, conductor reinforcement, and network reconfiguration, which led to substantial improvements. Voltage profiles returned to acceptable limits, transformers and line loading were reduced to safe ranges, and overall system efficiency increased. However, harmonic distortion levels remained above IEEE and IEC limits (8–11%), indicating that capacity expansion alone does not ensure power quality compliance. The installation of single-tuned (11th harmonic) and second-order high-pass harmonic filters was highly effective, reducing total harmonic distortion (THD) from 25 to 34% to below 5% (1 to 4%) and harmonic distortion below 3%, achieving full compliance with IEEE 519 standards. This demonstrates that combining infrastructure reinforcement with power quality mitigation is essential for sustainable EV integration. Supporting EV adoption requires strategic, multi-layered interventions rather than isolated upgrades. Without such coordinated planning, large-scale EV penetration will exacerbate grid instability, equipment stress, and power quality issues.