Power Flow as Intersection of Circles: A new Fixed Point Method
For power system engineers, this method improves robustness and convergence of power flow solvers, addressing a known bottleneck in existing fixed point approaches.
The paper proposes a new fixed point method for the power flow problem that uses circle geometry per bus to remove restrictions of existing methods. The algorithm finds intersections of circles efficiently and is shown to correctly find solutions when state-of-the-art methods fail, with greater robustness to bad initialization.
The power flow (PF) problem is a fundamental problem in power system engineering. Many popular solvers face challenges, such as convergence issues. One can try to rewrite the PF problem into a fixed point equation, which can be solved exponentially fast. But, existing methods have their own restrictions, such as the required AC network structure or bus types. To remove these restrictions, we employ the circle geometry per-bus via rectangular coordinate representation to embed our physical knowledge of operation point selection in PV curves. Each iteration of the algorithm consists of finding intersections of circles, which can be computed efficiently with high numerical accuracy. Such analysis also helps in visualizing PV curve to always select the high voltage solution. We compare the performance of our fixed point algorithm with existing state-of-the-art methods, showing that the proposed method can correctly find the solutions when other methods cannot. In addition, we empirically show that the fixed point algorithm is much more robust to bad initialization points than the existing methods.