A revised formulation of transmission capacity constraints in TCUC with consideration of instantaneous power flow limits

Abstract

The discrete time based transmission constraints are commonly used in transmission constrained unit commitment problems. However, the security operation requirements may be not satisfied by the solution of the discrete time based formulation for the instantaneous power flow may not be always within the secure limits. To address the problem, the paper proposes a way to revise the formulation of the discrete time based transmission constraints. Through considering the continuous time based transmission constraints, we could obtain the maximum possible deviation of the instantaneous line power flow from the average power flow. Rigorous secure limits for the average line power flow are then obtained and the transmission capacity constraints are thus revised. Numerical testing is performed for an IEEE 24-bus system and the results show that the revised formulation of transmission capacity constraints have a good performance on the security operation of the system.