Analysis of Harmonic Instability Induced by Lightning Strike in a LCC-HVDC System

In a ±500 kV/3000 MW line commutated converter based high voltage dc (LCC-HVDC) transmission system, divergent 125Hz harmonic voltage oscillation resulted in bipolar block after de line lightning strike fault. To study the phenomenon and find a solution, the characteristics of harmonic oscillation are first analyzed, and the harmonic transfer model of AC and DC system is established. Then HVDC control and protection cubicles in the loop simulation platform based on real time digital simulator (RTDS) is established and the harmonic instability phenomenon in field is reproduced. Further, the influence factors of oscillation damping are studied, based on the closed-loop simulation platform. Finally, the solution is proposed via control optimization and is verified on the simulation platform.