Turbine speed control system for downhole tool

摘要

Systems, methods, and devices are provided to generate a stable supply of electrical power in a drill string. In one example, a downhole turbine generator includes a turbine, a speed governor, and an alternator. The turbine may transform hydraulic power of a first fluid medium into rotational power of a rotating shaft. The speed governor may reduce the rotational power of the rotating shaft in a variable amount that depends on the speed of the rotating shaft. Specifically, weighted arms may shear a second fluid medium more when the speed is higher and less when the speed is lower. The shearing of the second fluid medium may generate a countervailing torque on the rotating shaft to reduce the rotational power of the rotating shaft. The alternator then may produce a generally stable supply of electrical power from the rotational power of the rotating shaft.

主权项

1. A downhole turbine generator comprising:
a turbine to transform hydraulic power of a first fluid medium passing through the turbine into rotational power of a rotating shaft a speed governor to reduce the rotational power of the rotating shaft by a variable amount depending on a speed of the rotating shaft, wherein the speed governor comprises weighted arms that shear a second fluid medium to a greater degree when the speed of the rotating shaft is higher and shear the second fluid medium to a lesser degree when the speed of the rotating shaft is lower, wherein the shearing of the second fluid medium generates a countervailing torque on the rotating shaft that reduces the rotational power of the rotating shaft; and an alternator configured to produce electrical power from the rotational power of the rotating shaft,wherein at least a part of each weighted arm of the speed governor is configured to shear the second fluid medium by extending farther away from the rotating shaft and further into the second fluid medium when the speed of the rotating shaft is higher.