Impacts of Single-Phase PV Injection on Voltage Quality in 3-Phase 4-Wire Distribution Systems

Single-phase solar photovoltaic (PV) injections in distribution systems can lead to voltage rise problems. This paper presents a mathematical framework to evaluate the phenomenon of rise in the voltage due to single-phase PV injections in 3-phase 4-wire distribution systems. The impacts of single-phase PV generation on neutral-point shifting and its effects on voltage unbalance criteria (e.g., NEMA standards) are thoroughly investigated. Injection of single-phase PV increases the voltage on that phase while decreasing the voltage on other phases, worsening the voltage unbalance problem. Furthermore, the influence of ZIP load models on voltage quality is investigated. This accurate load model can help reducing voltage unbalance factors for a given PV penetration level.