  In this short paper, we study the economic dispatch with adjustable
transformer ratio and phase shifter, both of which, along with the transmission
line, are formulated into a generalized branch model. Resulted nonlinear parts
are thereafter exactly linearized using the piecewise liner technique to make
the derived ED problem computationally tractable. Numerical studies based on
modified IEEE systems demonstrate the effectiveness of the proposed method to
efficiency and flexibility of power system operation.
