What is Islanding

The major purpose of uninterruptible power supply (UPS) systems is to supply regulated sinusoidal voltage at constant frequency and amplitude. UPS systems are gaining much popularity as a means of providing clean and continuous electricity to critical loads during any disturbances in main grid. Modern equipment is sensitive to power fluctuation and requires back up power supply for optimal performance. This chapter introduces a set of possible solutions so that uninterrupted power supply can be provided to emergency feeders and critical loads such as hospitals and communication systems. Different network configurations can be applied to micro-grid system for obtaining an uninterrupted power supply. Various hybrid energy and modern UPS systems for micro-grid along with their control techniques have been elucidated. A comparative assessment of all UPS technologies on the basis of cost, performance, and efficiency of the system has been presented.