Since power flow solution assumes that system is in steady state and also it is balanced. And that is why we normally sketch the network as single-phase network. How does OpenDSS perform the powerflow analysis in an unbalanced system?
Any technical paper link will be helpful. Thanks.
Last edit: Rakesh Belchandan 2019-06-07
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This is a topic we have discussed several times at this forum, feel free to use the search field in this forum to get more information. To start, take a look to this document:
In the pdf, it mentions: In words, after building Ysystem, the process starts with a guess at the system voltage vector, V0, and computes the compensation currents from each power conversion (PC) element to populate the Ipc vector.
Vn+1 = [Ysystem]-1 Ipc (Vn) n = 0, 1, 2, … until converged..
Also, In this formula, dimension of left hand side and right hand sides are not matching.
How do we calculate Ipc and how does it calculates Vn+1 if dimensions are not matching.
Thanks,
Rakesh
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They do match. The order of V, Y, and I is the number of nodes. Note that if there are no PCelements connected to a node, then the compensation current injected at that node is zero.
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Sorry if I am wrong here or I did not explain my previous question very well: By dimension, I do not mean the order of matrix but I mean right hand side in the formula is: [Ysystem]^-1 which is Zsystem, Ipc is current and Vn is previous iteration voltage so the product is: Impedance x current x voltage which is (some voltage)^2 where as in left hand side we only have new voltage value.
Is it just V = I*Z bottoms-up approach starting from the load side and matching it to the voltage at the head of distribution feeder? and adding any extra current injection in between in the network by PC elements if any.
If you can please provide me an example problem to explain this algorithm, it would be very helpful for me in which calculations are made manually using this algorithm.
Thanks and regards,
Rakesh
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Could i connect two voltage sources , that represents thevenin equivalent in two different nodes in the same network? What impact does it have on load flow?
Thanks and regards,
Verónica.
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Since power flow solution assumes that system is in steady state and also it is balanced. And that is why we normally sketch the network as single-phase network. How does OpenDSS perform the powerflow analysis in an unbalanced system?
Any technical paper link will be helpful. Thanks.
Last edit: Rakesh Belchandan 2019-06-07
Hello,
This is a topic we have discussed several times at this forum, feel free to use the search field in this forum to get more information. To start, take a look to this document:
https://sourceforge.net/p/electricdss/code/HEAD/tree/trunk/Version8/Distrib/Doc/OpenDSS%20Solution%20Technique.pdf
Best regards
Davis
Thanks.
Rakesh
Hello Davis,
In the pdf, it mentions: In words, after building Ysystem, the process starts with a guess at the system voltage vector, V0, and computes the compensation currents from each power conversion (PC) element to populate the Ipc vector.
Vn+1 = [Ysystem]-1 Ipc (Vn) n = 0, 1, 2, … until converged..
Also, In this formula, dimension of left hand side and right hand sides are not matching.
How do we calculate Ipc and how does it calculates Vn+1 if dimensions are not matching.
Thanks,
Rakesh
They do match. The order of V, Y, and I is the number of nodes. Note that if there are no PCelements connected to a node, then the compensation current injected at that node is zero.
Hi Roger,
Sorry if I am wrong here or I did not explain my previous question very well: By dimension, I do not mean the order of matrix but I mean right hand side in the formula is: [Ysystem]^-1 which is Zsystem, Ipc is current and Vn is previous iteration voltage so the product is: Impedance x current x voltage which is (some voltage)^2 where as in left hand side we only have new voltage value.
Is it just V = I*Z bottoms-up approach starting from the load side and matching it to the voltage at the head of distribution feeder? and adding any extra current injection in between in the network by PC elements if any.
If you can please provide me an example problem to explain this algorithm, it would be very helpful for me in which calculations are made manually using this algorithm.
Thanks and regards,
Rakesh
You misinterpreted the equation.
Ipc(Vn) neans the PCElement injection currents as a function of Vn. The injection currents are generally a nonlinear function of the voltages.
Thanks Roger. That helps.
Hello,
Could i connect two voltage sources , that represents thevenin equivalent in two different nodes in the same network? What impact does it have on load flow?
Thanks and regards,
Verónica.
Hello,
Sure, you can do it. Try it and check it out.
Best regards
Davis
Thanks Davis. I will do it.