변압기 기반 3상 전압변동 발생기의 출력전압 변동특성 해석

Abstract

This paper deals with an analysis of the output voltage variation characteristics of 3-phase voltage disturbance generator. The major components of the voltage disturbance generator are series transformers, sliding type autotransformers, and SCR thyristors. Although the generator has good features such as simple structure, high efficiency, cost-effective implementation, and easy control, it is inevitable to have some voltage drop across the series transformers and SCR thyristors. Therefore, it is necessary to analyse the voltage drop characteristics with the variation of load power as well as load power factor. The generator has several operation modes including normal, voltage sag, voltage swell, unbalance, and outage. In this paper, analysis is carried out in normal, voltage sag, and voltage swell mode, respectively. The simulation results in normal mode operation show that the voltage drop increases as the power factor decreases in lagging power factor at the same load power. The voltage drop at lagging power factor of 0.8 in full load condition is 3.54[%], by the way, the drop at leading power factor of 0.8 is 1.27[%]. Experimental set up is implemented and the test results are almost the same with those in simulation results. Simulations and experiments are carried out in voltage sag mode operation, too. The magnitude of voltage sag is set at 50[%] of the normal voltage. Each result of simulation and experiment is almost the same. The voltage drop at 0.8 leading, unity, and 0.8 lagging power factor is 1.9[%], 2.9[%], and 3.7[%], respectively. Similar simulations and experiments are carried out in voltage swell mode operation with the swell magnitude of 20[%] of the normal voltage. The results show that the voltage drop is 0.8[%], 2.8[%], and 3.7[%] when the load power factor is 0.8 leading, unity, and 0.8 lagging, respectively. It is expected that the analysis result can be used in the design and proper operation of the transformer based voltage disturbance generator.