Dear Sir or Madame, I'm a student at the Otto-von-Guericke University in Magdeburg, Germany and I'm about to get started in using Matpower for some network analysis problems in Low Voltage networks (230V rms). I try to calculate how the voltages at the busses/nodes change by adding more decentral energy sources like photovoltaics. I tried to use Matpower and have got some problems. It would be very nice if you could give me some advice in solving my modelling problem. I'd be very happy about any help.
At first view Matpower seems to be usefull for solving these problems. At first step I tried to build a network of only to busses (#01 to represent a energy source (transformator from medium voltage to low voltage, modelled as a generator) (#02: 100kW Load) in order to get to know Matpower itself. But I found a problem, which I can't solve right now: I have to set a baseMVA-Value and a base voltage. So I decided for some values. The lower the chosen MVA-Value the bigger the chance that the iteration won't converge. But in Low-Voltage I can't use some GVA or TVA-Values just in order to get it work, can't I?! For the Impedance of the branch, connecting both busses, I calculated values for a 300m piece of cable. Than I devided the Impedance-values by the baseImpedance in order to get p.u. Impedances as claimed by Matpower. The baseimpdance was calculated by Basevoltage * Basevoltage / Base power (MVA-Value) as written in my collection of formulas. But the impedances of the branch were so small that there's almost no powerloss and no decrease in the voltage between bus 1 & 2. I tried to scale up my Lowvoltage problem by setting 100MW for (real) 100kW and 230kV for 230V(real). But it didn't work. The modell didn't converge or gave wrong values back. So I want to know whats the best way to modell my Low-Voltage-problem in Matpower? In order to give you an idea, what I tried, here are some very short .m-files, which show my Problem at the decripted example. The file startbaresSkript is a runable file, which calculates the impedances and than passes them into the modell. The modell itself is just set up with some 'random' values just to create the structure and fill in correct values afterwards by using the "startbareSkript". Nomenclature: In Germany "U" is used for Voltage and the "_bez" in variable names express that Base-Values for p.u. - calculations are ment. I also tried for the Calculation of the base impedance to scale down the MVA-Base and the Base-Voltagein (kV) down to SI-measurement units, but it did'nt work either. Somehow I did'nt found a good way to cope with low voltage networks decripted in the manual. Can you help me?! Which settings have to be done to calculate a low-voltage-network with matpower? The concrete Data are: 230 V (RMS) between phase and neutral Line, 3 phase-model (Star-circuit, symmetric Loads and generations!) Loadvalues somewhere between 2-100 kW at each bus (fix Load/ fix generation) and a balancing generator representing the connected network to upper Voltage-Network-Layers... I would be really happy, if you could give me some hints, ideas or tipps to cope with that problem. Thanks a lot! Yours sincerely, Oliver Kopp Germany ___________________________________________________________ SMS schreiben mit WEB.DE FreeMail - einfach, schnell und kostenguenstig. Jetzt gleich testen! http://f.web.de/?mc=021192
erstesModell.m
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StartbaresSkript.m
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