Redundancy configuration strategy and condition maintenance arrangement of converter valves for MMC-HVDC transmission systems considering both reliability and economy

Abstract

The converter valve is a key equipment in the flexible DC transmission system, and in order to coordinate its reliability and economy, the redundant configuration strategy and condition maintenance arrangement of the converter valve are studied. Firstly, the reliability model of the converter valve bridge arm is established based on the half-bridge sub-module topology and k/n(G) model, and the Markov method is used to model the fault state transfer process of the converter valve bridge arm sub-module; secondly, for the condition maintenance problem, the impact of condition evaluation and the service age rollback effect brought by the maintenance are quantified, and the sub-module state difference caused by the maintenance is also considered, and the redundant configuration and condition maintenance Finally, the cycle time and average cost of condition maintenance under different redundancy degrees are derived by means of calculation examples. The results show that increasing the redundancy configuration can effectively extend the maintenance cycle and reduce the average cost. The strategy can provide a reference for the redundancy configuration and condition maintenance of the converter valve.