Subharmonic resonance occurrence in power

system more frequently. This paper used mathematical analysis

method for solving the nonlinear differential equations based on

the system equivalent diagram, and deduced the mathematical

expression of the subharmonic resonance, derived the relevant

affective factors of subharmonic resonance overvoltage

amplitude, and analyzed the influence of all relevant factors on

subharmonic resonance overvoltage in detail, finally validate the

conclusion of theoretical analysis using EMTP-ATP