HVDC harmonic calculation under asymmetric faults in the AC system based on particle swarm optimization

In the paper the modulation theory harmonic analysis is integrated with particle swarm optimization, an optimization algorithm of HVDC harmonic distribution under asymmetric faults in the AC system is put forward. Not only the nonlinear behavior of converter station rationally simulated and the interface between AC system and DC system is resolved with the improved dynamic phasor model, but also the calculation of harmonic can be more accurate by mean of particle swarm optimization. To verify the correctness and effectiveness of the algorithm, the method is used to analyze and calculate the harmonic of CIGRE HVDC system. Compared the results with those obtained by simulation using PSCAD/EMTDC software, it is found that the proposed method is accurate and effective, and provides the analysis basis of harmonic restrain, filter configuration and protection analysis in AC/DC system.