A step-dynamic voltage regulator based on cascaded reduced-power series transformers

• A step-dynamic voltage regulator has been introduced aiming costs reduction.
• The total power of transformers is similar to that used in the inverter-based DVR.
• The total power handled by switches is about 62.5% of that used in inverter-based DVR.
• Results obtained on a 5 kVA prototype demonstrate feasibility of proposed solution.
• The equipment time response is short enough to comply with CBEMA and ITIC curves.

The large number of computers and other sensitive electrical loads connected to power grid are directly affected by grid disturbances. The vast majority of these disturbances is related with voltage transients, such as voltage sags. This paper deals with a step-dynamic voltage regulator designed to protect the load against the effects of these voltage transients. The ideia is to use a simple structure based on the insertion of a cascaded reduced-power series transformers between grid and load. It makes possible the use of actual mains voltages to compensate and mitigate the disturbances. It will be shown that the proposed solution can fully compensate or mitigate the faults that occur more frequently in power systems. Experimental results obtained on a 5 kVA prototype demonstrate the feasibility of the proposed solution.