The various harmonic characteristic parameters have direct relation with the safety and stability of ultra-high voltage direct current（UHVDC） dry-type smoothing reactors.In order to determine the various harmonic characteristic parameters and estimate the performance of its operating conditions accurately

we put forward theoretical analysis and simulation results.The equivalent measuring principle in low current is verified and the current harmonic spectrum of UHVDC dry-type smoothing reactors under the double 12 pulse converter operating conditions are obtained.Then the measurement system and calculation process of the harmonic characteristic parameters are provided in this paper

and the characteristic parameters of a ±800 k V dry-type smoothing reactor are measured.The results show that

when power factor accuracy is 0.05%

and both voltage and current accuracy are 0.03%

the uncertainty of harmonic reactance test result is 0.11% calculated at 95% confidence level.The measurement system proposed in this paper can be used to measure characteric parameters of dry-type smoothing reactor accurately.All ressearch results are benificial for the product design

performance test

and evaluation on UHVDC dry-type smoothing reactor.