Recent opportunities for new hydropower generation in the United States have often been in non-powered dams and run-of-river type flows occurring in low-impact natural areas and unregulated conduits. At the same time, a changing water resource paradigm is challenging some existing generation in drought stricken areas where supply reservoirs behind many medium and high head units are at historically low levels. The result is a developing market space which is potentially best captured by machines capable of variable speed operation. Variable speed units have a wider range of operating conditions compared to their synchronous counterparts and have already proven their resilience through a 20+ year history in pumped hydro applications. This work develops a control scheme for variable speed hydropower units operating to deliver a set-point power through flow controlling gates. This control scheme increases both the hydrologic operating range of a unit as well as the speed of response to grid contingencies under droop and automatic generator control. Results from simulation are confirmed on hardware.
