Bourns College of Engineering

Electrical and Computer Engineering

  • Distribution System Operator (DSO) Market Design

    Three-phase ACOPF for Distribution Network

    The three-phase optimal power flow (OPF) problem has recently attracted a lot of research interests due to the need to coordinate the operations of large-scale and heterogeneous distributed energy resources (DERs) in unbalanced electric power distribution systems.

    The non-convexity of the three-phase OPF problem is much stronger than that of the single-phase OPF problem. Instead of applying the semidefinite programming relaxation technique, we advocate a convex iteration algorithm to solve the nonconvex three-phase OPF problem.

    To make the convex iteration algorithm computationally efficient for large-scale distribution networks, the chordal conversion based technique is embedded in the convex iteration framework. By synergistically combining the convex iteration method and the chordal based conversion technique, the proposed three-phase OPF algorithm is not only computationally efficient but also guarantees global optimality when the trace of the regularization term becomes zero.

    To further improve the computational performance, a greedy grid partitioning algorithm is proposed to decompose a single large matrix representing a distribution network to many smaller matrices. The simulation results using standard IEEE test feeders show that the proposed algorithm is computationally efficient, scalable, and yields global optimal solutions while resolving the rank conundrum.

    Scalability of the Proposed Chordal Conversion based Convex Iteration Algorithm


    Optimality of the Proposed Convex Iteration based Algorithm (Compared to Semidefinite Programming Relaxation Method)



    [J13] Wei Wang and Nanpeng Yu, "Chordal Conversion based Convex Iteration Algorithm for Three-phase Optimal Power Flow," IEEE Transactions on Power Systems, vol. 33, no. 2, March, 2018.

    [C11] Wei Wang and Nanpeng Yu, "LMP Decomposition with Three-Phase DCOPF for Distribution System," 2016 IEEE Innovative Smart Grid Technologies - Asia (ISGT Asia), Melbourne, VIC, pp. 1-8, 2016.

    Software Download

    User Manual and Software Code for Chordal Conversion based Convex Iteration Algorithm

    Software Manual

    Software Code

    Illustration of three-phase Locational Marginal Prices with phase unbalance constraint binding can be found in the figures below.