Thank you very much for your help and time. I very much appreciate it. On Wed, Mar 20, 2019 at 11:02 PM Ray Zimmerman <[email protected]> wrote:
> You cannot modify voltage angles independently and maintain feasibility > (respect the power balance constraints). In order to maintain feasibility > you must modify voltage angles and generator injections together along the > surface of power flow solutions. > > If you modify the voltage angles along the power flow surface, that is, > while maintaining feasibility, it will imply changes in generation which > will result in changes in cost. > > Ray > > > On Mar 20, 2019, at 1:25 PM, Arkan Arkan <[email protected]> wrote: > > I see. Thank you for your clarification. So, is there any trick and > solution to be able to change the output cost though manipulating the > voltage angles? > > Thanks. > > On Wed, Mar 20, 2019 at 7:33 PM Ray Zimmerman <[email protected]> wrote: > >> Ok, so you just want to evaluate the objective (or cost) function of the >> DC OPF at a given solution. The issue is that the cost function depends >> only on the generator injections, which are related to the voltage angles >> through the constraints. So if you take a DC PF solution and make changes >> to the voltage angles, without changing the generator injections, the >> result will be only infeasible power balance constraints with no change in >> the cost function. >> >> Simply put, manipulating the voltage angles will affect feasibility, but >> not cost. >> >> Ray >> >> >> On Mar 19, 2019, at 10:03 AM, Arkan Arkan <[email protected]> wrote: >> >> Dear Ray, >> >> Thank you so much for your response. I very much appreciate it. What I >> mean is a little bit different. Based on my understanding, I exactly need >> DC for my work. This is my understanding. When we run "rundcopf", after >> some calculations, the phase angles are obtained and then fed into the OPF >> function which finally gives us the total cost and the whole process is >> done as a function. Now, after computing the phase angles through PF and >> before feeding into OPF function to calculate the cost, I need to somehow >> change the values of calculated phase angles a little bit so that the final >> cost will be based on the manipulated (my values) phase angles. I tried to >> change the values of phase angles in different steps of the function but >> wasn't effective and the final calculated cost is like before change. >> Please let me know your thoughts on this. >> >> Thanks. >> >> Kind regards, >> Arkan >> >> On Tue, Mar 19, 2019 at 6:21 PM Ray Zimmerman <[email protected]> wrote: >> >>> I’m not sure I understand what you want to do. >>> >>> Let’s start with the DC OPF. It sounds like you’re saying you need to >>> run a DC OPF where you are directly specifying (constraining to a specific >>> value) some of the voltage angles. Is that correct? The problem is that >>> there are very few degrees of freedom in the voltage angles due to the >>> power balance constraints. I suspect that manipulating (constraining) the >>> voltage magnitudes directly will very quickly result in an infeasible OPF. >>> >>> But, you’re welcome to try. You can add user-defined linear constraints ( >>> A, l and u) to restrict the voltage angles. The first nb columns of A >>> correspond to the voltage angles. See section 6.3 and Chapter 7 in the >>> User’s Manual for more details. Simply use the VMIN and VMAX columns of >>> the bus matrix to restrict voltage magnitudes. >>> >>> Ray >>> >>> >>> >>> >>> On Mar 19, 2019, at 8:26 AM, Arkan Arkan <[email protected]> wrote: >>> >>> Dear All, >>> >>> I hope this note finds you well. I need to run optimal power flow (both >>> DC and AC) while the input values for phase angles and voltage magnitudes >>> are manipulated. In other words, how could I run OPF with desired values of >>> phase angles and voltage magnitudes? I know that I should change the values >>> on the way and in the middle of code but I wasn't able to find the right >>> place in MATPOWER. >>> >>> I would be so grateful if you could, please, help me in this regard. >>> >>> Thank you for your time and consideration. >>> >>> Kind regards, >>> Arkan >>> >>> >>> >> >
