Assessment of ATC Using Voltage and Transient Stability, Simultaneously

Methods for calculating Available Transfer Capability (ATC) of the transmission systems may be grouped under Static and Dynamic methods. This paper presents a fast dynamic method for ATC calculations, which considers both Transient Stability Limits and Voltage Stability Limits as terminating criteria. A variation of Energy Function Method is used to determine the transient stability limit and the determinant of the Jacobian matrix of the system is used as an index to determine the voltage stability limit. A novel method is used to approximately calculate this determinant. Combining these two methods, an algorithm that calculates ATC, based on both voltage and angle dynamic stability is presented. The advantage of this algorithm, besides considering both voltage and angle dynamic stability, is its high speed. This speed of calculation makes the algorithm a perfect

candidate to be used in screening contingencies and to determine those cases that need to be further analyzed. To demonstrate the validity, efficiency, and the speed of the new method, it is employed in the calculation of ATC for numerical examples with 2, 3, 7 (CIGREE), 10, 30 (IEEE) and 145 (Iowa State) buses.