Dear Ray, I am trying to convert AC power flow into DC one, to study the relation about them. via delete the reactive power variables, reactive power balance equations, all the voltages are assumed to 1.0 p.u., and also assume that the angles are too small that sina = a, so sin(a-b) = (a-b), meanwhile, cos(a-b) = 1.
But for the admittance matrix, I didn't ignore the Imaginary part j, I only consider cosa = 1 and sina = a (rad), is that right? And the same for the power injection at bus, I write in the way that' the power injected into the bus is equal to the power injected from those branches connected to this bus plus the power injected to the ground from this bus as the shunt power.' Also, I only consider cos(a-b) = 1 and sin(a-b) = (a-b), is that right? But unfortunately, when I run the DC model, It returns 'OPF not solved to optimality', It seems very strange. Do you think are there any wrong about my consideration for DC model change? And do you have any suggestion about the DC changing, please? Best regards, Qi Wang
