A compensator design for the aged hydro electric power plant speed governors

•We developed a model for an aged Hydro Electric Power Unit including backlash effect, which is not available in the literature.•A limited number of on-line site tests are sufficient for the generation of the model, making a minimum impact on availability of the HEPP unit.•We developed a new method to control turbine of an aged HEPP unit that has mechanical backlashes. In order to achieve this objective, we compared two control approaches and selected the outperforming one.•We applied the developed method on site in a newly developed and manufactured speed governor and obtained successful results.•We compared actual site results with the old plant performance and showed the improvement.

This paper presents a method to design and enhance the performance of speed governors for aged Hydroelectric Power Plants (HEPP) utilizing limited number of online site tests. First, the mathematical model for the governor is generated using plant parameters. Afterwards, the aging and backlash effects are added to the model in order to match the simulation outputs with the site measurements. The feed forward and Ziegler–Nichols (ZN) methods are examined in order to mitigate the impact of backlash. Between these methods the former one is selected since it also provides island-mode stability. The updated speed governor is applied to Gezende HEPP governor and performance progress is observed.