Modern methods of controlling micro hydropower plants with an asynchronous generator

This overview is dedicated to issues of controlling micro hydropower plants that possess an asynchronous generator (a squirrel-cage induction motor), which converts the energy of water flow—a promising alternative source of energy—to electric energy. Modern “green electronics” allows producing cheap and reliable micro hydropower plants and ensures stability of their output parameters amidst undefined and variable load and water-flow characteristics. The modes of self-excitation with no load and under load are given. The article describes design solutions based on various topologies of power converters specially designed for solving the set control problem, and describes two topologies using a direct current link with uncontrolled and controlled rectifiers, as well as a topology with a STATCOM system. Their advantages and disadvantages are discussed, and the potential of this approach to building a micro hydropower plant based on asynchronous generators is demonstrated.