Abstract
This paper presents a compensation method for unbalanced voltage through active and reactive power control by utilizing a smart inverter that improves the voltage unbalance index and detects an unbalanced state of voltage magnitude and phase, and thus enhances power quality by minimizing the voltage imbalance. First of all, this paper presents an analysis of a mathematical approach, which demonstrates that the conventional voltage unbalanced factor (VUF) using the symmetrical component cannot correctly detect the imbalanced state from index equations; and by only minimizing the VUF value, it cannot establish a balanced condition for an unbalanced state of the voltage profile. This paper further discusses that intermittent photovoltaic (PV) output power and diversified load demand lead to an unexpected voltage imbalance. Therefore, considering the complexity of unbalanced voltage conditions, a specific load and an PV profile were extracted from big data and applied to the distribution system model. The effectiveness of the proposed scheme was verified by comparing VUF indices and controlling the active and reactive power of a smart inverter through a numerical simulation.
Highlights
A power system is designed based on energy security, economic efficiency, and safety requirements at the generation, transmission, and distribution level
The PV connected phase is randomly selected, and the output thereafter is chosen from the clustering profile so that unbalanced states are mixed in a complicated manner
A mathematical approach elucidated the undetectable unbalance state and revealed that this undetectable unbalanced state occurs when renewable energy sources (RES) was interconnected to the system
Summary
A power system is designed based on energy security, economic efficiency, and safety requirements at the generation, transmission, and distribution level. Despite a large number of power quality indicators [4], previous voltage adjustment is not considered for phase unbalance of the voltage in the optimization problem [5,6,7,8,9]. This consideration could be different on the voltage level, and if the Energies 2020, 13, 4623; doi:10.3390/en13184623 www.mdpi.com/journal/energies. As reported in [9,10,11] the compensation devices’ control magnitude of voltage must be maintained within an appropriate range as power security. This paper focuses on the voltage imbalance problem accompanying heavy load and unbalanced connection of RES, considering voltage magnitude and phase unbalance
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