Unbalanced SSSC modelling in the harmonic domain

This paper presents a non-linear harmonic domain model for the static synchronous series compensator (SSSC). The model incorporates a fundamental frequency three-phase power-flow and a harmonic converter representation. This combination accounts for system imbalance and the resultant non-characteristic harmonic generation. The proposed unified solution format uses a single iterative loop eliminating unnecessary assumptions regarding the operating point. The models performance is validated against time domain simulation for an unbalanced test system. This test system is then used to illustrate the impact of transmission lines on the harmonic performance of a static synchronous series compensator, particularly with respect to additional harmonic transfers. Reinforcing the importance of comprehensive three-phase modelling when considering flexible AC transmission system (FACTS) devices