An inrush current limiter as a solution of injection transformer oversizing in dynamic voltage restores

In this paper, the problem of injection transformer saturation in dynamic voltage restoration (DVR) applications is analyzed. The inrush currents caused by the injection transformer saturation are one of the most serious problems that affects to this kind of systems. The high values of these inrush currents can cause faults in the power electronic system or can generate trips of the converter overcurrent protection. Furthermore, the inrush currents provoke high voltage drops that distort the injected voltage. As a result, a bad dynamic restoration of the voltage during sags is obtained. The most adopted solution is the oversizing of the injection transformer, however this solution drastically increments the cost of the system. What the authors propose is a solution based in a DC reactor type inrush current limiter (ICL). This solution is based on a diode H-bridge and a DC reactor connected in series with the primary winding of the injection transformer. The use of this solution will reduce the oversizing requirements in the injection transformer, reducing the cost of the system.