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The emergence of high voltage conversion applications has resulted in a trend of using semiconductor device series associations. Series associations allow for operation at blocking voltages, which are higher than the nominal voltage for each of the semiconductor devices. The main challenge with these topologies is finding a way to guarantee the voltage balance between devices in both blocking and switching transients. Most of the methods that have been proposed to mitigate static and dynamic voltage unbalances result in increased losses within the device. This paper introduces a new series stack topology, where the voltage unbalances are reduced. This in turn, mitigates the switching losses. The proposed topology consists of a circuit that ensures the soft switching of each device, and one auxiliary circuit that allows for switching energy recovery. The principle for the topology operation is presented and experimental tests are performed for two modules. The topology performs excellently for switching transients on each of the devices. The voltage static unbalances were limited to 10%, while the activation/deactivation delay introduced by the lower module IGBT driver takes place in the dynamic unbalances. Thus, the switching losses are reduced by 40%, when compared to hard switching configurations. [ABSTRACT FROM AUTHOR]

This paper presents the results of a power quality study carried out in an industrial distribution system. The main objective of this study was to quantify the negative impact caused by voltage sags in industrial processes and its relationship to generated interruptions. A series of measurements of power quality variations were taken at the substation that feeds the circuit and at the point-of-common coupling of each industrial user. The new standard IEEE Std 1564-2014 “Guide for Voltage Sag Indices” was used to determine the indicators to assess the severity of voltage sags and also the calculation method. Sag severity was selected as it allows the calculation of the probability of voltage sags to generate interruptions in industrial processes or electrical equipment. Thus, an analysis of the quality of the supply voltage can be done. Severity was initially calculated at the substation that feeds the industrial circuit and later, at the point-of-common coupling of each user. Subsequently, the relationship between user interruptions and severity values was determined. Finally, recommendations of good engineering practices in industrial processes were done. [ABSTRACT FROM AUTHOR]

Practical applications, such as the incorporation of the a new theoretical approach in the definition of the instantaneous and average compensation objectives for active power filters (APFs) in multiphase systems and the description of a global indicator for the evaluation of the power quality are introduced in this paper. In order to obtain these applications, a generalized theory of instantaneous power for nonsinusoidal unbalanced multiphase systems is proposed. The instantaneous power tensor is defined based on the tensor product between vectors of voltage and current. In addition, the simulated results are included. [ABSTRACT FROM AUTHOR]