Thank you for your timely and valuable answers. Now I have my own answer with your help. In PDIPM method, the OPF solving process updates four variables (Pg, Qg, Um and Ua) simultaneously and obtain the best solution finally. The equation constraints (PF equations) don’t need to be satisfied during the iteration process, but at the solution. So there is no complete PF solving process in the OPF solving process by PDIPM.
Thanks very much! Best Wishes, Walter ________________________________ From: bounce-122001212-79707...@list.cornell.edu <bounce-122001212-79707...@list.cornell.edu> on behalf of Ray Zimmerman <r...@cornell.edu> Sent: Tuesday, October 31, 2017 1:56:21 AM To: MATPOWER discussion forum Subject: Re: A problem about the relationship between PF and OPF solving process The answer to your question is No. The reason is that the power flow equations are included as equality constraints in the OPF problem, which is formulated as a nonlinear programming problem (NLP). When using a primal-dual interior point solver for an NLP, the equality constraints are not typically satisfied at every iteration, only at the solution. For more details on the formulation and algorithm, see Section 3.4 in the MIPS User’s Manual<http://www.pserc.cornell.edu/matpower/docs/MIPS-manual-1.2.2.pdf> or Appendix A.4 in the MATPOWER User’s Manual<http://www.pserc.cornell.edu/matpower/docs/MATPOWER-manual-6.0.pdf>. Ray On Oct 30, 2017, at 5:35 AM, Sun Weigao <sunwei...@outlook.com<mailto:sunwei...@outlook.com>> wrote: Dear Matpower users, I have a confusing problem when I am doing some research to improve the optimization of PF problem and OPF problem both. I solve the PF problem by Newton-Rapfson (NR) method, and OPF problem by Primal-dual Interior Point method (PDIPM). I want to figure out the relationship between the PF and OPF solving process. Do we need a complete PF solving process (using NR) during the OPF solving process (using PDIPM)? In other words, Does the solving process of the OPF problem (using PDIPM) contains many PF calculations? If Yes, in which step the PF is calculated ? and if No, why ? I've been puzzled by this problem for a long time, please help if you clear the answer. Thank you very much. Sincerely, Walter
