According to your previous answers to my posts the difference is only between voltage constraints in order to distinguish the results with and without OLTC. But I expect with OLTC, according to some papers I have read, it should be greater than that without OLTC. I have confused and I don't know how can I compare the results? Could you please help me?
Best Wishes Silvio On Thu, Feb 23, 2012 at 17:47, Ray Zimmerman <[email protected]> wrote: > So, the only difference between the two cases are the voltage constraints > at the slack bus? If so, I would expect the losses (and therefore the > generation) to be greater in the case with the lower voltage. > > -- > Ray Zimmerman > Senior Research Associate > 419A Warren Hall, Cornell University, Ithaca, NY 14853 > phone: (607) 255-9645 > > > > > On Feb 23, 2012, at 11:24 AM, Silvio Miceli wrote: > > Practically I don't have OLTC. According to your comments to my posts: "1) > Exclude bus GSP and the OLTC from the model and let Tx be the slack bus > with a dummy generator and VMIN = VMAX = 1.078." So, when I compare the > results considering OLTC, i.e. constraints of voltage at the slack bus , > and without any constraint, i.e. Vmax=Vmin=1.06. In my idea, in the case > with OLTC and lower and limits the capacity should be higher that without > constraint? Am I right? > > Regards > > Silvio > > > > On Thu, Feb 23, 2012 at 17:16, Ray Zimmerman <[email protected]> wrote: > >> It's probably due to a difference in losses. There may be losses in the >> OLTC itself depending on the parameters and if the voltage profile is >> different the losses in the rest of the network will be different as well. >> >> -- >> Ray Zimmerman >> Senior Research Associate >> 419A Warren Hall, Cornell University, Ithaca, NY 14853 >> phone: (607) 255-9645 >> >> >> >> >> On Feb 23, 2012, at 11:00 AM, Silvio Miceli wrote: >> >> Dear Ray, >> >> As far as I know when we have an OLTC, the generated capacity is more >> than that in the case without OLTC (i.e. Vmin=Vmax=1.06 p.u.). When I >> running an OPF or runmarket, for example in the case57, I get more >> generated capacity in the case without OLTC compared to with OLTC. >> >> Best Wishes >> >> Silvio >> >> >> On Mon, Feb 13, 2012 at 16:09, Silvio Miceli <[email protected]>wrote: >> >>> Thank you so much for your helpful comments. >>> >>> Best Wishes >>> >>> Silvio Miceli >>> >>> >>> >>> On Mon, Feb 13, 2012 at 15:27, Ray Zimmerman <[email protected]> wrote: >>> >>>> I don't know what you mean by the first solution with and without the >>>> OLTC. In the first solution, I am assuming that the OLTC maintains the >>>> voltage at Tx at your target, so it is not in the model. I suppose if by >>>> "without OLTC" you mean that the OLTC is not keeping the voltage at the >>>> target, then you can simply set the VMIN and VMAX to 1.0 p.u. Or you could >>>> use the setup for the 2nd option, and simply run it once with the taps at >>>> the nominal setting. >>>> >>>> -- >>>> Ray Zimmerman >>>> Senior Research Associate >>>> 419A Warren Hall, Cornell University, Ithaca, NY 14853 >>>> phone: (607) 255-9645 >>>> >>>> >>>> >>>> >>>> On Feb 13, 2012, at 9:19 AM, Silvio Miceli wrote: >>>> >>>> Dear Prof. Zimmerman, >>>> >>>> I want to use first solution. It is much more easier than the second >>>> one. In this case, how can I compare the results with and without OLTC? >>>> >>>> Kind regards >>>> >>>> S.M. >>>> >>>> >>>> On Mon, Feb 13, 2012 at 15:07, Ray Zimmerman <[email protected]> wrote: >>>> >>>>> So it seems you could model it two different ways in MATPOWER. >>>>> >>>>> 1) Exclude bus GSP and the OLTC from the model and let Tx be the slack >>>>> bus with a dummy generator and VMIN = VMAX = 1.078. >>>>> 2) Include GSP and the OLTC, with a dummy generator at GSP (the slack >>>>> bus), with VMIN = VMAX = 1.0. In this case, you would have to iteratively >>>>> run the OPF, then update the tap setting until the voltage at Tx is close >>>>> enough to your target. I suppose you could use VMIN = VMAX = 1.078 at Tx >>>>> and then adjust the tap ratio until you get a feasible solution. You may >>>>> need to leave a small epsilon difference between VMIN and VMAX at GSP or >>>>> Tx >>>>> in order to get feasibility. >>>>> >>>>> I expect the results for the rest of the system to be (at least >>>>> nearly) identical in the two cases. >>>>> >>>>> -- >>>>> Ray Zimmerman >>>>> Senior Research Associate >>>>> 419A Warren Hall, Cornell University, Ithaca, NY 14853 >>>>> phone: (607) 255-9645 >>>>> >>>>> >>>>> >>>>> >>>>> On Feb 10, 2012, at 8:32 PM, Silvio Miceli wrote: >>>>> >>>>> >>>>> >>>>> The information of the network is as follows: >>>>> >>>>> The one-line diagram of a typical rural section of the Irish 38-kV >>>>> distribution network was shown in above Figure. The feeders are supplied >>>>> by one 31.5-MVA 110/38-kV transformer (capable of handling reverse power >>>>> flows). The voltage at the grid supply point is assumed to be nominal. In >>>>> the original configuration (no DG), the on-load tap changer at the >>>>> substation has a target voltage of 1.078 pu (41 kV) at the busbar, well >>>>> within the +-10% nominal voltage limits of Irish practice. >>>>> >>>>> Best Wishes >>>>> >>>>> Silvio Miceli >>>>> >>>>> >>>>> On Fri, Feb 10, 2012 at 23:07, Ray Zimmerman <[email protected]> wrote: >>>>> >>>>>> You haven't said which bus is your slack bus. Can I assume that it >>>>>> would be the one labeled GSP? I don't see a slack generator at that bus. >>>>>> Is >>>>>> the OLTC the *only* voltage control you have in the network? Is the >>>>>> voltage >>>>>> at GSP fixed? >>>>>> >>>>>> -- >>>>>> Ray Zimmerman >>>>>> Senior Research Associate >>>>>> 419A Warren Hall, Cornell University, Ithaca, NY 14853 >>>>>> phone: (607) 255-9645 >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> On Feb 10, 2012, at 2:51 PM, Silvio Miceli wrote: >>>>>> >>>>>> I want to have an OLTC at slack bus only in order to control >>>>>> centrally the network voltage (active network) as below figure. How can I >>>>>> compare the results with and without OLTC? with changing tap ratio or >>>>>> with >>>>>> changing voltage setpoints? >>>>>> >>>>>> <image.png> >>>>>> >>>>>> Best Wishes >>>>>> >>>>>> Silvio Miceli >>>>>> >>>>>> >>>>>> On Fri, Feb 10, 2012 at 20:43, Ray Zimmerman <[email protected]>wrote: >>>>>> >>>>>>> In order to understand clearly what you are trying to compare, I >>>>>>> would need to see the network topology. >>>>>>> >>>>>>> But, it both cases include the OLTC in the topology and in one case >>>>>>> you are modifying the tap ratio to control voltage and in the other you >>>>>>> are >>>>>>> simply modifying the generator voltage setpoints, then the two solutions >>>>>>> will not be equivalent. >>>>>>> >>>>>>> -- >>>>>>> Ray Zimmerman >>>>>>> Senior Research Associate >>>>>>> 419A Warren Hall, Cornell University, Ithaca, NY 14853 >>>>>>> phone: (607) 255-9645 >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Feb 10, 2012, at 10:46 AM, Silvio Miceli wrote: >>>>>>> >>>>>>> Dear Ray, >>>>>>> >>>>>>> As far as I know, taking into account the voltage at slack bus as >>>>>>> optimization variable is equal to have an OLTC. So, how can I compare >>>>>>> the >>>>>>> results with and without voltage control at slack? Can it be done >>>>>>> either by >>>>>>> changing the tap ratio or voltage limits? >>>>>>> Best Wishes >>>>>>> >>>>>>> Silvio Miceli >>>>>>> >>>>>>> >>>>>>> On Thu, Feb 9, 2012 at 18:57, Silvio Miceli <[email protected] >>>>>>> > wrote: >>>>>>> >>>>>>>> Dear Ray, >>>>>>>> >>>>>>>> 1. Can I say MATPOWER's OPF considers the power factor angle of >>>>>>>> generators as optimization variable? If not, how can I consider as >>>>>>>> optimization variable? >>>>>>>> >>>>>>>> 2. Also, according to one of your replies to a post with regards to >>>>>>>> considering the slack bus voltage as optimization variable, why you >>>>>>>> want to >>>>>>>> implement OLTC in MATPOWER? In my idea, considering the slack bus as >>>>>>>> optimization variable is equal to have an OLTC and consequently >>>>>>>> considering >>>>>>>> the secondary voltage as optimization variable. Because usually the >>>>>>>> OLTC is >>>>>>>> used in order to control the voltage of slack bus and in MATPOWER is >>>>>>>> already considered as optimization variable. If I am not right, please >>>>>>>> let >>>>>>>> me know? >>>>>>>> >>>>>>>> Best Wishes >>>>>>>> >>>>>>>> Silvio >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Wed, Feb 8, 2012 at 17:47, Ray Zimmerman <[email protected]>wrote: >>>>>>>> >>>>>>>>> On Feb 8, 2012, at 10:01 AM, Silvio Miceli wrote: >>>>>>>>> >>>>>>>>> 1. What kind of generator has been taken into account in MATPOWER >>>>>>>>> in Section 5.4.3 of MANUAL in order to consider the capability curve? >>>>>>>>> >>>>>>>>> >>>>>>>>> It is simply intended to be a piecewise linear approximation to >>>>>>>>> the kind of capability curve exhibited by many types of conventional >>>>>>>>> generators, such as this >>>>>>>>> one<http://images.pennnet.com/articles/hrm/cap/cap_coord%2003.gif> >>>>>>>>> from >>>>>>>>> Figure 2 in [1]. >>>>>>>>> >>>>>>>>> 2. I want to minimize losses instead of maximizing social welfare >>>>>>>>> considering offers and bids. How can I do it in MATPOWER? >>>>>>>>> >>>>>>>>> >>>>>>>>> The answer to this one is readily available in the list archives >>>>>>>>> ... e.g. >>>>>>>>> http://www.mail-archive.com/[email protected]/msg00817.html >>>>>>>>> >>>>>>>>> 3. How can I maximize profit for generators in MATPOWER instead of >>>>>>>>> maximizing Social welfare? >>>>>>>>> Also, by which formula I can obtain profits (for generators), >>>>>>>>> revenue and cost in MATPOWER? Could you please address it? >>>>>>>>> >>>>>>>>> >>>>>>>>> I'm not aware of a method to maximize profits, since that would >>>>>>>>> involve an objective that is a function of price, a very >>>>>>>>> unconventional >>>>>>>>> type of optimization problem. You can compute revenue directly as the >>>>>>>>> product of quantity and price, and the cost is available in the >>>>>>>>> dispatch >>>>>>>>> matrix returned by runmarket. See help idx_disp for a description of >>>>>>>>> each >>>>>>>>> column of the dispatch matrix. >>>>>>>>> >>>>>>>>> - Ray >>>>>>>>> >>>>>>>>> [1] >>>>>>>>> http://www.hydroworld.com/index/display/article-display/353952/articles/hydro-review/volume-28/issue-2/feature-articles/system-protection/coordinating-generator-protection-and-controls-an-overview.html >>>>>>>>> >>>>>>>>> -- >>>>>>>>> Ray Zimmerman >>>>>>>>> Senior Research Associate >>>>>>>>> 419A Warren Hall, Cornell University, Ithaca, NY 14853 >>>>>>>>> phone: (607) 255-9645 >>>>>>>>> >>>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>> >>>> >>> >> >> > >
