On Nov 25, 2008, at 11:16 AM, Mingyang Li wrote:
I am a new user of Matpower. I have two questions about the AC power flow algorithm in the latest version (v3.2) of Matpower: 1. How are the initial voltage values set at buses at the beginning? What are the voltage values given at reference bus and PV buses?
The initial voltages (angles and magnitudes) are set based on the values in the VA and VM columns in the bus matrix, with the exception of the reference and PV buses, whose magnitude is set equal to the corresponding VG column in the generator matrix.
2. What is the stop criteria of Newton method and fast decoupled flow method? I found that the parameter "tol", which seems to be the stop tolerance, is 0 as the second element in the vector "mpoption". However, in order to stop by the criteria "norm(Delta_P,inf)<tol", the tolerance must be a positive number.
The algorithms terminate when the largest mismatch (in p.u.) becomes smaller than the parameter "tol" defined by the 2nd element in mpoption, which has a default value of 1e-8. It also terminates if the specified max number of iterations is exceeded (defined in the 3rd or 4th element of mpoption, depending on the algorithm).
-- Ray Zimmerman Senior Research Associate 428-B Phillips Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645
