A 3-phase power quality disturbance generator is dealt with for the performance test of high power custom power devices such as DVR, SSTS, dynamic UPS, etc. The major components of the scheme are transformers, power diodes, and natural commutated SCR thyristors, which guarantee high reliability, high efficiency, and low implementation cost. Therefore, the scheme is especially suitable for high power applications. Detailed analysis and simulations are carried out for a system with input voltage of 3300VAC and 10MVA output power rating and the results show the usefulness of the scheme.