Modeling UPS and enhancing the capability by integrating renewable sources

Abstract

Power outage or power line disturbances have detrimental effect on the operation of critical loads like computer controlling important process or medical equipment. The study of power line disturbances were done in the first phase of the thesis. Uninterruptible Power Supply (UPS) is one of the means to provide back up during disturbances (like overvoltage, under-voltage, sags or swells) and outage. PS provides voltage regulation during power line disturbances and backup power during outage. Study on different UPS construction and range of operation had been completed in the second phase of this thesis. In the UPS there is a rechargeable battery, which supplies power to the load when the power supply is cut off for limited time period. Research papers on renewable energy shows significant improvement of UPS capacity if fuel cells are used in parallel with the battery backup. When the essential load exceeds maximum limit provided by battery, the fuel cell stack then can provide additional power to the extra load. As a result the limited capacity of the battery is possible to overcome by introducing fuel cells in case of excess demand .Study on fuel cell and its promising feature to enhance the UPS capacity is also the part of the thesis.