Novel four-bridge PWM static VAr compensator

A novel four-bridge PWM static VAr compensator is presented. Theoretical analysis shows that the harmonic pairs of [(2k+1)f_s ±f] and [(4k+2)f_s±f] generated in each bridge are effectively eliminated through appropriate phase shift control. To satisfy the same 5% total harmonic distortion requirement, this new compensator can work at 200 Hz, which is much lower than the previously reported 1.9 kHz of a single-bridge PWM static VAr compensator. The efficiency is increased and reliability is enhanced. The fairly low switching frequency and multiple-bridge structure facilitate its use in a high-power VAr compensator since a GTO can be employed as the power switch. Theoretical analysis was verified through simulations and experimental results