In order to analyze the relationship between the voltage sag immunity and the parameter configuration of the adjustable speed drive(ASD)

this paper studies the theoretical calculation approaches of voltage sag immunity and the parameter design of ASD. There are two key parameters discussed here. One is the threshold of DC under-voltage protection

the other is the capacitance on DC side. Firstly

the relationship between voltage sag immunity and the two key parameters is analyzed and the mathematical expressions are given to calculate the voltage sag immunity of ASD in the most severe case. Secondly

depending on the demand of voltage sag immunity

the mathematical expressions are given to help the parameter design. Thirdly

the testing platform and simulation model for voltage sag immunity of ASD are developed. Finally

by the comparison of calculation

simulation and testing results

the effectiveness of the proposed approaches has been verified. The proposed approaches can reduce the hard work of the operational test and improve the efficiency of the parameter design

which can be considered as the basis of solution for the compatibility between power suppliers and end-users.