Design and Analysis of a Hybrid-Excitation Generator for Hydropower Applications

The paper presents a performance analysis of a hybrid-excitation salient-pole generator for hydropower applications. The proposed machine combines a conventional field winding with permanent magnets within the rotor poles to reduce excitation losses. A hybrid-excitation machine was compared to a traditional electrically excited machine using twodimensional finite element method simulations across multiple operating points, including different power factors and load levels. Results have shown that the hybrid-excitation machine achieves an average field current reduction of approximately 9%, consequently decreasing field winding losses. Loss analysis has shown an overall loss reduction of around 2.4%, with particular improvements in the inductive operating region. The resulting efficiency increase of 0.22% contributes to meaningful longterm energy and cost savings. A comparison of material cost revealed a higher initial cost of the hybrid-excitation machine due to permanent magnets. However, the analysis has shown a return on investment of 9.6 years under proposed operating conditions. The research confirmed that rotor hybridization represents an effective approach for efficiency improvement and reduced operating cost of small hydropower generators.