Variable-speed operation of hydropower plants: past, present, and future

Abstract

In This article, the state of the art in the variable-speed operation of hydropower plants is reviewed, with a focus on pumped-storage hydropower. Relevant literature is reviewed to address the benefits of variable-speed operation for both power systems and hydropower facilities. Two main configurations to enable variable-speed operation-the doubly fed induction machine (DFIM) and the converter-fed synchronous machine (CFSM)-are discussed and compared. The article addresses the technology and energy policies of the past, present, and future and points out how the motivation, services, value, and technology of variable-speed hydropower plants have been subject to considerable change.