Comparison of Static Phase Shifter and Unified Power Flow Controller-Based Interphase

The basic interphase power controller (IPC) presents the interesting features of simplicity and low cost but is less flexible than most flexible ac transmission system controllers. A compromise performance can be achieved by replacing the phase shifting transformers with a reduced rating dual unified power flow controller (UPFC) resulting in a unified IPC. The comparison of the basic, phase shifter-based, with a new UPFC-based, control logic is the main goal of this paper. The control variables of the dual UPFC are computed based on an optimization procedure to minimize a given cost function. The results show the higher capability of the proposed logic not only to control the current flow through the transmission line but also to achieve this task with lower branch currents that should lead to reduced power losses.