Load independent voltage drop characteristics of a voltage disturbance generator with nonlinear load

A 3-phase voltage disturbance generator applicable for the operation of nonlinear load is proposed. To test the performance of the custom power devices such as DVR, SSTS, dynamic UPS, etc., a voltage disturbance generator is necessary. The proposed generator has good features of high reliability, low cost, simple structure, high efficiency, and reduced voltage drop in normal operation. The main switching device of the proposed generator is SCR thyristor, and all the thyristors are turned off under the natural commutation condition. Therefore, high reliability of the generator can be obtained. The circuit analysis and operating principle of the proposed scheme are described in each mode of voltage sag, swell, outage, and unbalance. Simulation results show the usefulness of the proposed scheme.