Universal Modular Permanent Magnet Synchronous Generator for Small Low-Head Hydropower Plants

Abstract

Small hydropower plants (SHPs) can significantly exploit the unutilised hydropower potential in Europe. In particular, this applies to run-of-the-river power plants with low heads. Variable speed technology, high-efficiency, and low-speed synchronous generators with permanent magnets (PMSGs) can significantly improve the efficiency of such SHPs. Unfortunately, the cost of design and implementation of PMSGs for a specific SHP remains significantly high compared to a classic induction generator. This study proposes to reduce the cost of PMSG production by applying a new idea of modular construction of the generator. The proposed solution assumes the possibility of using a universal segment to implement generators of different power (through parallel connection) and rotational speed (by reconfiguring the stator winding). The generator parameters are determined on the basis of an analysis of Poland's hydropower potential and matched to the hydro set with a discharge of 1 to 10 m3/s and heads of 1.5 to 3.5 m. A full-size prototype of a 120 kW three-segment generator is developed. Prototype tests for various configurations of segment windings confirmed that the idea of a modular generator is possible for industrial implementation. However, further optimization work related to improving the efficiency, symmetry, and repeatability of segments is recommended.