Analysis of the Impact of Smart Inverter Volt-VAR Curve Settings on Voltage Fluctuation of Power Distribution System; [배전계통의 전압변동에 스마트 인버터의 Volt-VAR 곡선 설정이 미치는 영향 분석]

초록

As renewable energy sources are increasingly integrated into power systems to mitigate the climate crisis, the adoption of smart inverters—key devices for enhancing the stability of distributed generators like photovoltaic (PV) systems—is being encouraged. Consequently, research on the impact of smart inverters on potential power system fluctuations is also growing. In this paper, a simulated distribution system was constructed to model load power variations and undervoltage conditions caused by single-line-to-ground faults. By configuring various Volt-VAR curves for the smart inverter, its effects on voltage recovery and line loss in the distribution system were analyzed. Our findings confirmed that a smaller slope in the Volt-VAR curve provided a more significant compensation effect for overall voltage drops in the distribution system. Also, setting an excessively large slope could lead to voltage oscillation due to reactive power output, thereby negatively impacting the entire system’s stability. Two causes for oscillation phenomena in smart inverters were identified, stemming from their computation and control methods. Despite these inherent operational characteristics, experimental results further confirmed that mitigating these oscillations was achievable by adjusting the slope of the Volt-VAR curve to a gentler setting. © The Korean Institute of Electrical Engineers

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