METHOD FOR CONTROLLING VOLTAGE OF CAPACITOR OF MODULAR MULTILEVEL CONVERTER SUBMODULE, AND RECORDING MEDIUM IN WHICH COMPUTER-READABLE PROGRAM FOR EXECUTING SAID METHOD IS RECORDED

摘要

Provided is a method comprising the steps of: determining whether capacitor voltages of the submodules of a modular multilevel convertor are within a predetermined allowable range; when the capacitor voltages are outside the allowable range, turning off charging/discharging switches for all submodules to be charging/discharging; comparing a predetermined reference switch-on number with a current switch-on number, which is the number of switches currently turned on among the charging/discharging switches for the submodules; and when the reference switch-on number is greater than the current switch-on number, turning on switches selected from currently turned-off charging/discharging switches for the corresponding submodules on a predetermined switch-on basis of the difference obtained by subtracting the current switch-on number from the reference switch-on number, and when the reference switch-on number is smaller than the current switch-on number, turning off switches selected from currently turned-on charging/discharging switches for the corresponding submodules on a predetermined switch-off basis of the difference obtained by subtracting the reference switch-on number from the current switch-on number.