Three-Phase Optimal Power Flow for Low-Voltage Distribution Network

Against the backdrop of large-scale distributed photovoltaics being integrated into low-voltage distribution networks, which gives rise to problems like overvoltage, increased power loss, and voltage unbalance, this study puts forward a day-ahead optimal power flow approach for low-voltage distribution networks that takes three-phase unbalance into consideration. First off, drawing on the three-phase Distflow power flow framework, a dynamic optimization model is built to coordinate active power and reactive power within low-voltage distribution networks. This model incorporates both continuous and discrete parameters, categorizing it as a mixed-integer non-convex nonlinear optimization problem from a mathematical standpoint. Secondly, the second-order cone relaxation method is utilized to convexify the three-phase power flow equations, thereby converting the initial problem into a mixed-integer second-order cone programming model that enables efficient solution. Finally, case investigations are conducted on a 21-node low-voltage distribution network test system, and the outcomes confirm the practicality and effectiveness of the presented optimal approach.