Three-Phase Dynamic Phasor Modeling of Line Commutated Converter with Harmonics

The dynamic phasor model, based on the generalized averaging method, is widely utilized in power electronic modeling due to its high computational efficiency. However, modeling line commutated converters (LCCs) with dynamic phasors poses challenges, primarily because deriving the switching functions proves to be complex. Existing literature commonly assumes linearity during commutation to derive these switching functions, which can result in inaccuracy under specific conditions. This paper addresses this challenge by deriving (1) a more explicit expression for the analytical equations of the DC side, and (2) a more accurate expression on AC side switching function based on the line voltage during commutation period. Additionally, the paper investigates the influence of delay and commutation angles on harmonics and provides insights of harmonic inclusion for different accuracy requirements. The proposed improvements are validated using the IEEE 34-bus system with an integrated LCC system.