Study of power flow control by unified power flow controller

Abstract

In the past, power systems were relatively simple and self-sufficient; power exportation and importation were rare and few. At that time it was generally understood that power systems could not be controlled fast enough to handle the system dynamic conditions. Traditionally systems were designed with fixed or mechanically switched series and/or shunt reactive compensations, together with voltage-regulating and phase-shifting transformer, to optimize line impedance, voltage variation, and power flow control under steady state or slowly changing load conditions. In recent years, energy, environment, right-of-way, and capital cost issues have delayed the construction of both generation facilities and new transmission lines, while the demand f o relectric power has continued to grow. These issues have challenged power system engineers today to use the existing transmission facilities to greater effect and efficiency.