Optimal Power Flow Paper 8: A computational Study of Preprocesessed Linear Approximations to Convex Constraints in the Iterative Linear IV-ACOPF Formulation

and Executive Summary In this paper, we test the effect of preprocessed and iterative linear cuts on the convex constraints maximum voltage and maximum current in iterative linear approximation of the current voltage IV formulation of the ACOPF ILIV‐ACOPF problem. The nonconvex constraints are linearized using iterative first order Taylor series approximation. The ILIV‐ACOPF is solved as a single linear program or a sequence of linear programs. The ILIV‐ACOPF model is tested on the 14‐bus, 30‐bus, 57‐bus and 118‐bus IEEE test systems. The execution time and the quality of the solution obtained from the ILIV‐ACOPF are compared for different test systems and benchmarked against the equivalent nonlinear ACOPF formulation. The results show execution time up to 8 times faster and solutions close to the nonlinear solver. The performance of different algorithmic parameters varies depending on the test problem. As the number of preprocessed cuts for each bus and line increases, the relative error decreases. The results indicate that 16 to 32 constraints are the best number of preprocessed constraints in a tradeoff between accuracy and solution time. The marginal value of more than 32 and maybe 16 preprocessed constraints in this setting is negative. Nevertheless, the number of preprocessed constraints can be set based on the performance and requirements of the specific problem being solved. Using iterative cuts often results in faster convergence to a feasible solution. When solving without using iterative cuts, the solution is within 18% of the best‐known nonlinear feasible solution; with iterative cuts, the solution is within 2.5% of the best‐known nonlinear solution. At 16 or 32 preprocessed constraints, solution time is up to about 8 times faster than the nonlinear solver IPOPT . Disclaimer: The views presented are the personal views of the authors and not the Federal Energy Regulatory Commission or any of its Commissioners.