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