Mitigating Unbalances in Low-voltage Distribution Network by Coordinatedly Operating Phase-switching Devices and SVG

As distributed generations, especially rooftop solar PVs, penetrate in low voltage distribution network (LVDN), existing unbalance issue can be worsened, resulting in a series of operation problems or deteriorated power supply quality. To address this issue, dynamic switching devices (PSDs) and static VAR generator (SVG) are efficient options in practical operations. However, coordinatedly operating the two devices from the system operator's perspective needs further exploration. This paper, after presenting the SVG model particularly for dispatch purpose in LVDN, formulates the operation of LVDN as a mixed-integer non-convex programming (MINCP) problem based on three-phase optimal power flow (TUOPF). To efficiently solve the challenging problem, the MINCP is reformulated as mixed-integer linear programming (MILP) based on reasonable assumptions, making it possible to employ off-the-shelf solvers. Simulations based on a modified IEEE system and a practical system in Australia demonstrates the efficiency of the proposed method and the benefits brought by these flexible devices.