A New Computation Method for Thermal Capacity and Voltage Constraints TTC Considering Mho Relay Operating Conditions

Abstract

This paper proposes a new computation method for Total Transfer Capability (TTC) with respect to thermal and voltage magnitude limits. TTC is formulated as an optimization problem and solved by The Primal-Dual Interior Point Method (PDIPM). In stressed power system, mho relays are possible factors for causing cascading failures because of their unnecessary operations caused by decrease in voltages in heavy load conditions. Therefore, in order to consider mho relay characteristics, the relay operating conditions are taken into account in the optimization problem as constraints to compute TTC. The effectiveness of the proposed method is demonstrated through IEEE 57 bus system model.