Abstract: A control system is provided. The control system includes a turbine controller that is configured to generate at least a first signal that is representative of pitch control commands for a plurality of turbine blades and a second signal that is representative of the pitch control commands for the turbine blades. A first pitch controller is coupled to the turbine controller, wherein the first pitch controller is configured to receive the first signal and to implement the pitch control commands for each of the turbine blades in response to receiving the first signal. A second pitch controller is coupled to the turbine controller and to the first pitch controller, wherein the second pitch controller is configured to receive the second signal and to implement the pitch control commands to each of the turbine blades when the first pitch controller is unable to implement the pitch control commands.

Abstract: A control system is provided. The control system includes a turbine controller that is configured to generate at least a first signal that is representative of pitch control commands for a plurality of turbine blades and a second signal that is representative of the pitch control commands for the turbine blades. A first pitch controller is coupled to the turbine controller, wherein the first pitch controller is configured to receive the first signal and to implement the pitch control commands for each of the turbine blades in response to receiving the first signal. A second pitch controller is coupled to the turbine controller and to the first pitch controller, wherein the second pitch controller is configured to receive the second signal and to implement the pitch control commands to each of the turbine blades when the first pitch controller is unable to implement the pitch control commands.

Abstract: A method for shutdown of a wind turbine having one or more wind turbine blades includes detecting an operational condition of the wind turbine that calls for an expedited or emergency shutdown of the wind turbine by a manner other than normal pitch control shutdown. Upon detection of the operational condition, one or more air brake flaps configured on each of the turbine blades is deployed by removing power to a fail-safe actuator operatively coupled to each of the air brake flaps. The fail-safe actuator is configured to hold the respective air brake flap at a retracted position relative to a suction side of the turbine blade in a powered state of the fail-safe actuator and to release the air brake flap for automatic deployment to an open position upon loss of power to the fail-safe actuator.

Abstract: A wind turbine blade includes an air brake flap flush mounted within a recess in the suction side of the blade. The air brake flap is actuatable from a retracted position within the recess to an open position wherein the air brake flap extends transversely or vertically from the suction side. A fail-safe actuator is operatively coupled to the air brake flap and is configured to hold the air brake flap at the retracted position in a powered state of the actuator and to release the air brake flap to the open position upon loss of power to the actuator.

Abstract: A method for shutdown of a wind turbine having one or more wind turbine blades includes detecting an operational condition of the wind turbine that calls for an expedited or emergency shutdown of the wind turbine by means other than normal pitch control shutdown. Upon detection of the operational condition, one or more air brake flaps configured on each of the turbine blades is deployed by removing power to a fail-safe actuator operatively coupled to each of the air brake flaps. The fail-safe actuator is configured to hold the respective air brake flap at a retracted position relative to a suction side of the turbine blade in a powered state of the fail-safe actuator and to release the air brake flap for automatic deployment to an open position upon loss of power to the fail-safe actuator.

Abstract: An engine operating system includes an exhaust aftertreatment device and a fuel delivery system for providing fuel to the engine so as to cause the engine's air/fuel ratio to vary on a periodic basis. The exhaust aftertreatment device has a window of maximum operating efficiency characterized by storage and release of an exhaust constituent within the aftertreatment device. A controller operates the fuel delivery system and performs a statistical analysis of signals from an exhaust constituent concentration sensor downstream of the exhaust aftertreatment device, so as to assure that the exhaust aftertreatment device is being operated within its window of most efficient operation.