In modern society, the utility power grid is supposed to guarantee load management, demand side management, as well as to use the market price of electricity and forecasting of energy (eg: based on wind and solar renewable sources) in order to optimise the whole electrical distribution system. An optimised power system is expected to have the following characteristics: high efficiency, high availability, good quality of service and high level of security, which leads to the concepts of distributed generation and smart-grid. This book discusses different emerging technologies, principles and applications of power electronics and hydroelectric power. Some of the topics discussed include parallel three-phase back-to-back converters; risk management of hydropower projects; and cascade converters for wide conversion ratios.