Dear Ray, Thank you for the clarification!
Kind Regards, Alexandra Alexandra Kapetanaki PhD Student Electrical Energy & Power Systems Group, School of Electrical & Electronic Engineering Ferranti Building (B18), The University of Manchester, M13 9PL, United Kingdom Tel: +44 (0) 161 306 2263; Mobile: +44 (0) 7857 598179 ________________________________ From: [email protected] [[email protected]] on behalf of Ray Zimmerman [[email protected]] Sent: 17 June 2013 14:12 To: MATPOWER discussion forum Subject: Re: maximise DG No real significance. The important thing for maximizing DG output is the difference between the cost of conventional supply and the DG cost. I just mentioned a large positive cost to ensure that there would be a substantive difference. -- Ray Zimmerman Senior Research Associate B30 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Jun 16, 2013, at 3:03 PM, Alexandra Kapetanaki <[email protected]<mailto:[email protected]>> wrote: Dear Ray, Dionisis, I have included DG in a transmission network as well and I have set zero cost for the DGs. My aim is to maximize the output of the DG but I can not understand where is the benefit of setting a large positive cost on the slack bus gen. Can you please clarify me the difference of not using the actual cost cooefficients for all the regular generators? Thank you in advance, kind Regards, Alexandra Kapetanaki Alexandra Kapetanaki PhD Student Electrical Energy & Power Systems Group, School of Electrical & Electronic Engineering Ferranti Building (B18), The University of Manchester, M13 9PL, United Kingdom Tel: +44 (0) 161 306 2263; Mobile: +44 (0) 7857 598179 ________________________________ From: [email protected]<mailto:[email protected]> [[email protected]<mailto:[email protected]>] on behalf of Ray Zimmerman [[email protected]<mailto:[email protected]>] Sent: 15 June 2013 17:01 To: MATPOWER discussion forum Subject: Re: maximise DG Your logic sounds correct. You might also just try putting a large positive cost on the slack bus gen and zero costs on all of the DGs. It should be equivalent. It could be that there is some tradeoff between maximizing DG and minimizing losses and the value used for DG cost affects this tradeoff. -- Ray Zimmerman Senior Research Associate B30 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Jun 13, 2013, at 7:38 AM, Dionisis Stamatiadis <[email protected]<mailto:[email protected]>> wrote: Hi, I am using MatPower during my MSc thesis in which I study the behaviour of a storage system connected to a distribution network with distributed generators (DGs). My objective is to maximise the DG export subject to the grid's constraints (voltages, line limits) - objective function: max Pdg. I though that putting the costs of the main grid's generator (slack bus) equal to zero, and the DGs' costs a negative value I would get the maximum DG output. However, it seems that this is not the case since I get a different DG export for different negative costs. If I was right, then the DG export (maximum achieved subject to system constraints) should be the same for every negative cost. Do you think that my thinking is wrong? What would you suggest me to do in order to maximise the DG export. I read section 5.3 but I think that I do not have to add more variables and costs, since I can model DG units as plain generators. Thank you in advance, Dionisis
