Fast evaluation methods of ATC with thermal constraints and voltage stability constraints

This paper proposes two fast calculation methods of available transfer capacity (ATC). These two methods evaluate ATC with thermal constraints (thermal ATC) and ATC with voltage stability constraints (voltage ATC) respectively. The proposed method of thermal ATC assessment utilizes ´compensation theorem´ and ´principle of superposition´ and it doesn´t require the power flow calculations for each (n-1) contingency. In the voltage ATC evaluation, a composite index concerning voltage stability is proposed and the severest faults are effectively identified by a contingency screening method. Moreover, voltage simulation techniques are also applied to take into account the VQC control effect. Numerical examples using model power systems including a large-scale power system show that the proposed methods can make ATC calculation considering thermal and voltage stability limits much faster than the conventional one. The proposed method considering the voltage stability constraints can evaluate ATCs in just a couple of seconds, even if it is applied to a large-scale power system.