A testing system for the performance evaluation of electrical machines under realistic voltage fluctuations

The electrical voltage fluctuations and their negative effects on industrial and domestic apparatuses represent one of the most interesting topics of research in the field of Power Quality. Early studies investigated the behavior of different types of lamps in presence of voltage amplitude modulations and the design of light flicker meters. In realistic conditions, the observed voltage fluctuations have usually more complex shapes, that are quite different from the rectangular or sinusoidal amplitude modulations defined in the IEC standard. In this paper we are mostly concerned with the development of an innovative testing system for the performance evaluation of electrical machines under realistic voltage fluctuations, whose parameters are suggested by international organizations. The desired amplitude fluctuations are obtained by introducing time variable current absorption in an ad hoc power electronic apparatus which is parallel connected to the electrical loads, as it frequently occurs in the real working conditions. A PC, hosting a DAQ board and an IEEE 488 board, performs the data acquisition of electrical and mechanical quantities and controls the firing unit. The proposed system can be adopted for testing electrical motors and transformers, as well as adjustable speed drives, by reproducing a wide set of voltage fluctuation shapes for long duration testing. The proposed technique can be also adopted for the generation of transitory voltage imbalances.