Dear all, I'm starting to model and analyse power systems and I've decided to use Matpower. I have a question regarding creating admittance matrix which is needed to performe a load flow. Text books say that diagonal elements of this matrix is a sum of admittances all branches connected to a particular node and 'include also the admittance to ground of line charging susceptance and any other fixed admittance to ground' (from 'Power System Analysis' by H.Saadat). There is also presented a way how to convert impedance diagram of a system into the admittance diagram and the admittance matrix of such a systm is calculated. The diagonal elements include also admittance of the current sources. (chapter 6 of the book)
My question is: why in Matpower (but also in examples of power flow calculations from above book) we don't consider admittance of sources/loads? Is this because we assume that there are 'ideal power sources/consumers' with constant power and if we considered internal admittances, their power would be variable and depending on the system load and therefore couldn't be PQ-nodes anymore? Similarly for PV- and slack node? If not, what is a reason for that? I cannot find any explicit explanation in the literature. Thank you in advance and best regards, Mateusz Wanka
