RESEARCH ON MODULATION STRATEGY OF CASCADED STATCOM BASED ON CPD - SPWM

For multi - level structure , PWM technology is one very critical aspect, it relates to the quality and efficiency of the system output voltage cascaded STATCOM. Based on the principle of multiple modulation strategies analyzed and compared, including vertical carrier phase shift modulation, the carrier level phase shift modulation technique, the unipolar vertical multiplier carrier phase shifting CPD - SPWM technique as Cascaded STATCOM modulation techniques. Vertical carrier modulation technique can make STATCOM relatively low switching frequency to achieve a relatively high equivalent switching frequency, thereby to reduce t he harmonic content of the output current.