Using the UPFC and GUPFC Controllers to Maximize Available Transfer Capability (ATC)

Abstract

This paper focuses on studying the effect of the unified power flow controller (UPFC) and generalized unified power flow controller (GUPFC) to maximize the Available Transfer Capability (ATC). The normalized sensitivity factors technique is used, can be approximately computed, to determine the ATC of a test system, considering a variety of system limits. The basic Voltage Stability Constrain Optimal Power Flow (VSC-OPF) solution that does not consider contingencies is used for determining the sensitivity of power flows with respect to the critical loading parameter. Then, based on this solution and assuming a small variation of the loading parameter, compute the power flows again by solving critical power flows function. Then the sensitivity of system loading factor and N-1 contingency criteria technique is used to determine an optimal location of the UPFC and GUPFC controller. Finally, using proper models of the UPFC and GUPFC controllers, the effects of this Flexible AC Transmission System (FACTS) controller on the system ATC are studied. The IEEE 57- bus and 118-bus is used as the test system for validity, computing the system ATC for a given generation and loading pattern. All realistic control limits, as well as voltage dependent loads, are used in the ATC computation, with and without FACTS controller. The GUPFC can so strong influence the system in controlling or enhancement the ATC as good as power flow possible is compared with the UPFC. Keyword: UPFC, GUPFC. ATC, loading parameter, VSC-OPF