Changing the p.u. base for power also changes the p.u. base for impedance, so unless you update the p.u. impedance values in the branch matrix, this corresponds to a change in the actual impedances of the branches which does change the solution, as expected.
Regarding voltages, again, this is related to the fact that the impedances are already expressed in p.u. So, since the calculations are all done in terms of p.u., changing the p.u. voltage base does not affect the p.u. solution in any way. -- Ray Zimmerman Senior Research Associate 419A Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Jan 2, 2013, at 6:30 AM, ???? <[email protected]> wrote: > Happy New Year! > I got confused when I used matpower4.1 to compute the power flow.The default > of system base power,taking case9.m for example, is mpc.baseMVA = > 100.Logically the value of the base power dose not affect the calculated > result.However, when mpc.baseMVA = 200 ,running 'runpf(case9)',the power flow > result is different,such as losses and the branch charging.That confused me a > lot. > And there is one more problem.No matter how I change the base voltage(baseKV) > in the mpc.bus of case9.m,the power flow is the same.As the default of the > pu(Vm) is 1, the real voltage varies with the change of base > voltage.Therefore the power flow should not be the same. > Thank you for sharing your experience.
