Analysis on Commutation Failures in Multi-Infeed HVDC Transmission Systems in North China and East China Power Grids Planned for UHV Power Grids in 2015

Based on the summer peak load operation mode in the planning of UHV power grids in North China,Central China and East China in 2015,the commutation failures in multi-infeed HVDC transmission systems in North China and East China power grids are researched in depth by the electromechanical transient simulation software PSD-BPA.Research results show that the unipolar/bipolar blocking occurring in any DC line in North China and East China UHV power grids will not lead to commutation failure in other DC lines of these power grids;three phase-to-ground faults occurring near converter buses in majority DC inverter stations in North China power grid will not lead to commutation failure in other DC lines;three phase-to-ground faults occurring in main transmission channels of East China power grid and that occurring near the converter buses of inverter stations may lead to simultaneous commutation failures in multi DC lines.However,the durations of these ensuing commutation failures are very short,and the DC system can resume normal operation rapidly and the power grid can remain stable without taking any measures.The occurrence of commutation failures at DC transmission lines in East China power grid can be effectively suppressed by reactive power compensation with static var compensators(SVC).