Hi Tobias, For your first question, please see the relevant derivation in Section 3.7 of the User’s Manual<https://matpower.org/docs/MATPOWER-manual-7.1.pdf>. This describes the formulation used by MATPOWER. I suppose it is possible that some DC power flow implementations also include the approximation that the tap ratio is 1. Off the top of my head, I’m can’t really comment on the impact of including (or not) that approximation.
Regarding the second question, getting an exact match between MATPOWER and the commercial software would require both correct parameters for MATPOWER and an identical model. It seems likely that the commercial software could be using a more sophisticated model that does include the iron loss current and magnetizing current, as mentioned by Carlos in the message you referenced. If that is the case, I suppose his suggestions could possibly be used to adjust some parameters (e.g. add shunts) to more closely approximate the commercial software solution. On the other hand, given the state of the work on a new network and modeling layer for MATPOWER, called MP-Element<https://github.com/MATPOWER/mp-element/> (made public only days ago), now is probably a good time to call for help to work on improved transformer model implementations for MATPOWER. Ray On Oct 30, 2020, at 6:02 AM, Hoffmann, Tobias <tobias4.hoffm...@tu-dortmund.de<mailto:tobias4.hoffm...@tu-dortmund.de>> wrote: Dear all, in my work I’m trying to validate a module that creates a mpc with required grid information (buses, topology information, loads, …). Therefore I have two questions related to the correct modelling of the MATPOWER case file. 1) After some adjustments of the model, I receive very accurate results for the DC power flow in matpower compared with a commercial powerflow tool. The decisive setting was the neglection of the parameters in the TAP column for the transformers. The only place where the TAP column is considered for the DC power flow is inside the function makeBdc below (line 64/65). ____________________________________________________________________________________ [Bbus, Bf, Pbusinj, Pfinj] = makeBdc(baseMVA, bus, branch … stat = branch(:, BR_STATUS); " OutmailID: 125086863, List: 'matpower-l', MemberID: 82861091 SCRIPT: "ones at in-service branches b = stat ./ branch(:, BR_X);" TCL MERGE ERROR ( 10/30/2020 10:39:49 ): "invalid command name "ones" series susceptance tap = ones(nl, 1); " OutmailID: 125086863, List: 'matpower-l', MemberID: 82861091 SCRIPT: "default tap ratio = 1 i = find(branch(:, TAP));" TCL MERGE ERROR ( 10/30/2020 10:39:49 ): "invalid command name "default" indices of non-zero tap ratios tap(i) = branch(i, TAP); " OutmailID: 125086863, List: 'matpower-l', MemberID: 82861091 SCRIPT: "assign non-zero tap ratios b = b ./ tap; _____________________________________________________________________________________ After I received the results, I’m still trying to understand the influence of the column TAP (the transformer off nominal turns ratio). According to my actual understanding of the DC power flow only the reactance has an influence on the resulting flows. May someone be so kind to explain me the consideration of the TAP column in the makeBdc-function. I already found the old post here but would like to understand it even better (https://www.mail-archive.com/matpower-l@cornell.edu/msg00320.html). 2) My second question is related to a proper validation of the AC-power flow. Here I have an issue with the modelling of transformers as I get different results between MATPOWER compared to a commercial powerflow tool. As I describe above the result for the DC-power flow are already quite accurate. Below I show the same input data for the transformer. It is a 2-winding transformer connecting two different voltage levels without any shifting. I’m trying to validate the AC-power flow in a small test grid with five nodes and the slack at “NODE2_21”. ----- 2 WINDING TRANSFORMER BLOCK ----- _________1_________2_________3_________4_________5_________6_________7_________8_________9 Node 1 |Node 2 |O|S|U1 |U2 |Sn |R(Ohm)|X(Ohm)|B(uS) |G(uS) |I(A) |Element Name| ##T NODE5_81 NODE2_21 1 0 347.0 242.0 240.0 1.1200 44.100 -28.0000 1.0000 400 TR-1 To calculate the right values for the branch matrix I use the following values from the depending transformer: - baseKV_from = 347 kV - baseMVA = 100 MVA - zbase_from = basekV_from^2 / baseMVA - BR_R = 1.12 (Ohm) / zbase_from - BR_X = 44.1 (Ohm) / zbase_from - BR_B = -28 (uS) * 10^-6 * zbase_from My results for the branch matrix are - BR_R = 0,00093 - BR_X = 0,03662 - BR_B = -0,03371 Without modelling a load/generation at node “NODE5_81” I receive quite different results in voltage magnitude/angle. - MAPTOWER o VM = 1,04480948; VA= 0,000897843 - Commercial powerflow tool o VM = 0,998756671; VA = -0,000364748875 I suppose that it has do something with the modelling of the transformer losses in matpower. But I don’t have a clue how to get more accurate results. I also tried the approach to model the losses as suggested here (https://www.mail-archive.com/matpower-l@cornell.edu/msg02291.html). If someone can give me a hint where to look at, I would be very thankful! Thank you very much. With kind regards, Tobias Hoffmann Wichtiger Hinweis: Die Information in dieser E-Mail ist vertraulich. Sie ist ausschließlich für den Adressaten bestimmt. Sollten Sie nicht der für diese E-Mail bestimmte Adressat sein, unterrichten Sie bitte den Absender und vernichten Sie diese Mail. Vielen Dank. Unbeschadet der Korrespondenz per E-Mail, sind unsere Erklärungen ausschließlich final rechtsverbindlich, wenn sie in herkömmlicher Schriftform (mit eigenhändiger Unterschrift) oder durch Übermittlung eines solchen Schriftstücks per Telefax erfolgen. Important note: The information included in this e-mail is confidential. It is solely intended for the recipient. If you are not the intended recipient of this e-mail please contact the sender and delete this message. Thank you. Without prejudice of e-mail correspondence, our statements are only legally binding when they are made in the conventional written form (with personal signature) or when such documents are sent by fax. --_000_25F97A78071F4F29B13D3C5066D16FF4cornelledu_ Content-Type: text/html; charset="utf-8" Content-ID: <5a9bcccdd0d0a84ea5ea52918c945...@namprd04.prod.outlook.com> Content-Transfer-Encoding: base64 <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""> Hi Tobias, <div class=""><br class=""> </div> <div class="">For your first question, please see the relevant derivation in Section 3.7 of the <a href="https://matpower.org/docs/MATPOWER-manual-7.1.pdf"; class="">User’s Manual</a>. This describes the formulation used by MATPOWER. I suppose it is possible that some DC power flow implementations also include the approximation that the tap ratio is 1. Off the top of my head, I’m can’t really comment on the impact of including (or not) that approximation.</div> <div class=""><br class=""> </div> <div class="">Regarding the second question, getting an exact match between MATPOWER and the commercial software would require both correct parameters for MATPOWER and an identical model. It seems likely that the commercial software could be using a more sophisticated model that does include the iron loss current and magnetizing current, as mentioned by Carlos in the message you referenced. If that is the case, I suppose his suggestions could possibly be used to adjust some parameters (e.g. add shunts) to more closely approximate the commercial software solution. </div> <div class=""><br class=""> </div> <div class="">On the other hand, given the state of the work on a new network and modeling layer for MATPOWER, called <a href="https://github.com/MATPOWER/mp-element/"; class="">MP-Element</a> (made public only days ago), now is probably a good time to call for help to work on improved transformer model implementations for MATPOWER.</div> <div class=""><br class=""> </div> <div class=""> Ray</div> <div class=""><br class=""> </div> <div class=""><br class=""> </div> <div class=""><br class=""> <div><br class=""> <blockquote type="cite" class=""> <div class="">On Oct 30, 2020, at 6:02 AM, Hoffmann, Tobias <<a href="mailto:tobias4.hoffm...@tu-dortmund.de"; class="">tobias4.hoffm...@tu-dortmund.de</a>> wrote:</div> <br class="Apple-interchange-newline"> <div class=""> <meta name="Generator" content="Microsoft Word 15 (filtered medium)" class=""> <style class=""><!-- /* Font Definitions */ @font-face {font-family:Wingdings; 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font-family:"Courier New";} @list l2:level3 {mso-level-number-format:bullet; mso-level-text:\F0A7; mso-level-tab-stop:none; mso-level-number-position:left; text-indent:-18.0pt; font-family:Wingdings;} @list l2:level4 {mso-level-number-format:bullet; mso-level-text:\F0B7; mso-level-tab-stop:none; mso-level-number-position:left; text-indent:-18.0pt; font-family:Symbol;} @list l2:level5 {mso-level-number-format:bullet; mso-level-text:o; mso-level-tab-stop:none; mso-level-number-position:left; text-indent:-18.0pt; font-family:"Courier New";} @list l2:level6 {mso-level-number-format:bullet; mso-level-text:\F0A7; mso-level-tab-stop:none; mso-level-number-position:left; text-indent:-18.0pt; font-family:Wingdings;} @list l2:level7 {mso-level-number-format:bullet; mso-level-text:\F0B7; mso-level-tab-stop:none; mso-level-number-position:left; text-indent:-18.0pt; font-family:Symbol;} @list l2:level8 {mso-level-number-format:bullet; mso-level-text:o; mso-level-tab-stop:none; mso-level-number-position:left; text-indent:-18.0pt; font-family:"Courier New";} @list l2:level9 {mso-level-number-format:bullet; mso-level-text:\F0A7; mso-level-tab-stop:none; mso-level-number-position:left; text-indent:-18.0pt; font-family:Wingdings;} ol {margin-bottom:0cm;} ul {margin-bottom:0cm;} --></style><!--[if gte mso 9]><xml> <o:shapedefaults v:ext="edit" spidmax="1026" /> </xml><![endif]--><!--[if gte mso 9]><xml> <o:shapelayout v:ext="edit"> <o:idmap v:ext="edit" data="1" /> </o:shapelayout></xml><![endif]--> <div lang="DE" link="#0563C1" vlink="#954F72" class=""> <div class="WordSection1"> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">Dear all,<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class=""><o:p class=""> </o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">in my work I’m trying to validate a module that creates a mpc with required grid information (buses, topology information, loads, …). Therefore I have two questions related to the correct modelling of the MATPOWER case file.<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class=""><o:p class=""> </o:p></span></p> <p class="MsoListParagraph" style="margin-left:18.0pt;mso-add-space:auto;text-indent:-18.0pt;mso-list:l0 level1 lfo1"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">1)<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">After some adjustments of the model, I receive very accurate results for the DC power flow in matpower compared with a commercial powerflow tool. The decisive setting was the neglection of the parameters in the TAP column for the transformers. The only place where the TAP column is considered for the DC power flow is inside the function makeBdc below (line 64/65).<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">____________________________________________________________________________________<o:p class=""></o:p></span></p> <p class="MsoNormal" style="text-autospace:none"><span lang="EN-GB" style="font-size: 10pt; font-family: "Courier New";" class="">[Bbus, Bf, Pbusinj, Pfinj] = makeBdc(baseMVA, bus, branch<o:p class=""></o:p></span></p> <p class="MsoNormal" style="text-autospace:none"><span lang="EN-GB" style="font-size: 10pt; font-family: "Courier New";" class="">…<o:p class=""></o:p></span></p> <p class="MsoNormal" style="text-autospace:none"><span lang="EN-GB" style="font-size: 10pt; font-family: "Courier New";" class="">stat = branch(:, BR_STATUS); </span><span lang="EN-GB" style="font-size:10.0pt;font-family:"Courier New";color:forestgreen" class="">" TCL MERGE ERROR ( 10/30/2020 10:39:49 ): "extra characters after close-quote ones at in-service branches</span><span lang="EN-GB" style="font-size:12.0pt;font-family:"Courier New"" class=""><o:p class=""></o:p></span></p> <p class="MsoNormal" style="text-autospace:none"><span lang="EN-GB" style="font-size: 10pt; font-family: "Courier New";" class="">b = stat ./ branch(:, BR_X); </span><span lang="EN-GB" style="font-size:10.0pt;font-family:"Courier New";color:forestgreen" class="">%% series susceptance</span><span lang="EN-GB" style="font-size:12.0pt;font-family:"Courier New"" class=""><o:p class=""></o:p></span></p> <p class="MsoNormal" style="text-autospace:none"><span lang="EN-GB" style="font-size: 10pt; font-family: "Courier New";" class="">tap = ones(nl, 1); </span><span lang="EN-GB" style="font-size:10.0pt;font-family:"Courier New";color:forestgreen" class="">%% default tap ratio = 1</span><span lang="EN-GB" style="font-size:12.0pt;font-family:"Courier New"" class=""><o:p class=""></o:p></span></p> <p class="MsoNormal" style="text-autospace:none"><span lang="EN-GB" style="font-size: 10pt; font-family: "Courier New";" class="">i = find(branch(:, TAP)); </span><span lang="EN-GB" style="font-size:10.0pt;font-family:"Courier New";color:forestgreen" class="">%% indices of non-zero tap ratios</span><span lang="EN-GB" style="font-size:12.0pt;font-family:"Courier New"" class=""><o:p class=""></o:p></span></p> <p class="MsoNormal" style="text-autospace:none"><span lang="EN-GB" style="font-size: 10pt; font-family: "Courier New";" class="">tap(i) = branch(i, TAP); </span><span lang="EN-GB" style="font-size:10.0pt;font-family:"Courier New";color:forestgreen" class="">%% assign non-zero tap ratios</span><span lang="EN-GB" style="font-size:12.0pt;font-family:"Courier New"" class=""><o:p class=""></o:p></span></p> <p class="MsoNormal" style="text-autospace:none"><span lang="EN-GB" style="font-size: 10pt; font-family: "Courier New";" class="">b = b ./ tap;</span><span lang="EN-GB" style="font-size:12.0pt;font-family:"Courier New"" class=""><o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">_____________________________________________________________________________________<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class=""><o:p class=""> </o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">After I received the results, I’m still trying to understand the influence of the column TAP (the transformer off nominal turns ratio). According to my actual understanding of the DC power flow only the reactance has an influence on the resulting flows. <o:p class=""> </o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class=""><o:p class=""> </o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">May someone be so kind to explain me the consideration of the TAP column in the makeBdc-function. I already found the old post here but would like to understand it even better (<a href="https://www.mail-archive.com/matpower-l@cornell.edu/msg00320.html"; class="">https://www.mail-archive.com/matpower-l@cornell.edu/msg00320.html</a>).<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class=""><o:p class=""> </o:p></span></p> <p class="MsoListParagraphCxSpFirst" style="margin-left:18.0pt;mso-add-space:auto;text-indent:-18.0pt;mso-list:l0 level1 lfo1"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">2)<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">My second question is related to a proper validation of the AC-power flow. Here I have an issue with the modelling of transformers as I get different results between MATPOWER compared to a commercial powerflow tool. As I describe above the result for the DC-power flow are already quite accurate. Below I show the same input data for the transformer. It is a 2-winding transformer connecting two different voltage levels without any shifting. I’m trying to validate the AC-power flow in a small test grid with five nodes and the slack at “NODE2_21”.<o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpLast" style="margin-left:18.0pt;mso-add-space:auto"> <span lang="EN-GB" style="font-family:Akkurat" class=""><o:p class=""> </o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">----- 2 WINDING TRANSFORMER BLOCK -----<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">_________1_________2_________3_________4_________5_________6_________7_________8_________9<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">Node 1 |Node 2 |O|S|U1 |U2 |Sn |R(Ohm)|X(Ohm)|B(uS) |G(uS) |I(A) |Element Name|<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class=""><o:p class=""> </o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">##T<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">NODE5_81 NODE2_21 1 0 347.0 242.0 240.0 1.1200 44.100 -28.0000 1.0000 400 TR-1<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class=""><o:p class=""> </o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">To calculate the right values for the branch matrix I use the following values from the depending transformer: <o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpFirst" style="text-indent:-18.0pt;mso-list:l2 level1 lfo2"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">-<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">baseKV_from = 347 kV<o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpMiddle" style="text-indent:-18.0pt;mso-list:l2 level1 lfo2"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">-<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">baseMVA = 100 MVA<o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpMiddle" style="text-indent:-18.0pt;mso-list:l2 level1 lfo2"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">-<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">zbase_from = basekV_from^2 / baseMVA<o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpMiddle" style="text-indent:-18.0pt;mso-list:l2 level1 lfo2"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">-<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">BR_R = 1.12 (Ohm) / zbase_from<o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpMiddle" style="text-indent:-18.0pt;mso-list:l2 level1 lfo2"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">-<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">BR_X = 44.1 (Ohm) / zbase_from<o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpLast" style="text-indent:-18.0pt;mso-list:l2 level1 lfo2"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">-<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">BR_B = -28 (uS) * 10^-6 * zbase_from<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">My results for the branch matrix are <o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpFirst" style="text-indent:-18.0pt;mso-list:l1 level1 lfo3"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">-<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">BR_R = 0,00093<o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpMiddle" style="text-indent:-18.0pt;mso-list:l1 level1 lfo3"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">-<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">BR_X = 0,03662<o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpLast" style="text-indent:-18.0pt;mso-list:l1 level1 lfo3"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">-<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">BR_B = -0,03371<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">Without modelling a load/generation at node “NODE5_81” I receive quite different results in voltage magnitude/angle. <o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpFirst" style="text-indent:-18.0pt;mso-list:l1 level1 lfo3"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">-<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">MAPTOWER<o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpMiddle" style="margin-left:72.0pt;mso-add-space:auto;text-indent:-18.0pt;mso-list:l1 level2 lfo3"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:"Courier New"" class=""><span style="mso-list:Ignore" class="">o<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">VM = 1,04480948; VA= 0,000897843<o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpMiddle" style="text-indent:-18.0pt;mso-list:l1 level1 lfo3"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:Akkurat" class=""><span style="mso-list:Ignore" class="">-<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">Commercial powerflow tool<o:p class=""></o:p></span></p> <p class="MsoListParagraphCxSpLast" style="margin-left:72.0pt;mso-add-space:auto;text-indent:-18.0pt;mso-list:l1 level2 lfo3"> <!--[if !supportLists]--><span lang="EN-GB" style="font-family:"Courier New"" class=""><span style="mso-list:Ignore" class="">o<span style="font:7.0pt "Times New Roman"" class=""> </span></span></span><!--[endif]--><span lang="EN-GB" style="font-family:Akkurat" class="">VM = 0,998756671; VA = -0,000364748875<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class=""><o:p class=""> </o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">I suppose that it has do something with the modelling of the transformer losses in matpower. But I don’t have a clue how to get more accurate results. I also tried the approach to model the losses as suggested here (<a href="https://www.mail-archive.com/matpower-l@cornell.edu/msg02291.html"; class="">https://www.mail-archive.com/matpower-l@cornell.edu/msg02291.html</a>). If someone can give me a hint where to look at, I would be very thankful!<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class=""><o:p class=""> </o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">Thank you very much. With kind regards,<o:p class=""></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-family:Akkurat" class="">Tobias Hoffmann<o:p class=""></o:p></span></p> <p class="MsoNormal"><o:p class=""> </o:p></p> <p class="MsoNormal"><span style="font-family:Akkurat" class=""><o:p class=""> </o:p></span></p> </div> <font face="Arial" class=""><br class=""> <font size="2" class=""><em class="">Wichtiger Hinweis: Die Information in dieser E-Mail ist vertraulich. Sie ist ausschließlich für den Adressaten bestimmt. Sollten Sie nicht der für diese E-Mail bestimmte Adressat sein, unterrichten Sie bitte den Absender und vernichten Sie diese Mail. 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