Analysis of the uninterruptible power supply influences to the power grid

Systems of uninterruptible power supplies (UPS) are indispensable part of many industrial plants, transportation, telecommunications and other systems, enabling their proper functioning and supply with stable DC and AC voltages. The structure of power section of the UPS system typically consists of a DC link and two converters which perform an indirect AC conversion with bidirectional energy flow. This article provides an overview of the various topologies and structures of the advanced UPS system. UPS input rectifier circuits used to achieve power factor correction (PFC) are specifically described in accordance with the requirements to the load powered by the UPS system. In addition to comparative analysis of these circuits, their main advantages and disadvantages are described. The simulation models of the power and control part of the selected solutions are elaborated for program package MATLAB and PLECS as well. In addition, simulation experiments based on developed models are carried out in order to analyze solution functionality, in terms of PFC and UPS influence to power grid.