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 >>>>>>> >>>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>> >>>> >>> >>> >> >> >
