United Technologies Corporation

John P Patrick

Kermit I Harner

Joseph M Kos

Robert B Goodman

Kenneth F Vosseller

A blade feathering system for wind turbines includes a feather actuator (299), control means (330 and 335) operatively connected thereto and an adjustment means (340) operatively connected to the control means for selectively varying the rate of operation of the feather actuator for feathering the wind turbine blades (10 and 15) at a variable rate.

Blade feathering system for wind turbines

Damping of the primary bending mode of a tower (12) mounting a wind turbine having a control (36) for providing a pitch blade angle reference signal (40) to modulate the pitch of the turbine blades (1) through a pitch change mechanism (38) for constant power is provided by generating the pitch blade angle reference signal as the integral (104) of the summation (266) of a torque/power controlling blade pitch angle reference rate signal (98) with an estimated acceleration signal (255) generated by filtering (250, 252, 254) the blade pitch angle reference signal (40) with the following transfer function ##EQU1##

Predicted motion wind turbine tower damping

An accelerometer (1) disposed on the support tower (12) of a wind turbine electric generating system in the vicinity of the rotor (10, 16) thereof provides a signal (1) indicative of acceleration of the tower in the direction of the rotor rotational axis. The signal (2) is passed through a band-pass filter (4) for summation (9) with a torque/power controlled (100) blade pitch angle reference rate signal (98), the integral (104) of which provides a blade pitch angle reference signal (40) to control the pitch angle of the rotor blades (10) through a pitch change mechanism (38), thereby to provide additional, positive aerodynamic damping to the tower while modulating blade angle for constant torque/power in response to wind turbulence.

Motion responsive wind turbine tower damping

A blade pitch angle control for a wind turbine-generator establishing an optimum power or torque reference signal which, when operating conditions so warrant, is not limited by the nominal torque or power ratings of various turbine generator components. The reference signal is indicative of a maximum blade angle setting for safe operation of the wind turbine. An integral or lag compensation circuit for enhanced transient and steady-state operation may be employed.

Blade pitch angle control for a wind turbine generator

Fluid temperature control system for providing a supply fluid at a select temperature by warming or cooling a first fluid with a controlled flow of a second fluid. The control of the second fluid flow is achieved by a modulation valve adjustable in response to the pressure of a supply of servo fluid which is itself adjusted in response to the temperature of the supply fluid. The adjustment of the servo fluid pressure by the control system is such that the change in servo fluid pressure from a steady state condition is initially great, diminishing with time to a lesser, steady state value, thereby enhancing the transient response of the control system.

Fluid temperature control system

In an integral rocket-ramjet having a combustor which initially serves as a rocket combustion chamber for booster propellant, and after the booster propellant is expended serves as a ramjet combustor where fuel and air are burned, a fuel control system is described for the ramjet stage by which ram burner light-off is automatically initiated upon transition from rocket to ramjet propulsion. The fuel control regulates fuel flow to the combustor over the entire flight regime and responds to operating conditions to provide a light-off schedule, to stabilize the shock wave at the air inlet, to provide a maximum fuel-to-air ratio limit, to limit the maximum vehicle Mach number, and to prevent lean burner blowout by providing a minimum fuel-to-air ratio limit. Mach number limiting and air inlet margin limiting are performed in closed loop fashion, while the other functions are scheduled or open loop controls. The closed loop functions are performed by scheduling a ratio of combustion chamber pressure to a reference pressure, and comparing this ratio to the ratio of the pressures as measured, any error therebetween being used to produce a desired fuel flow to combustion chamber pressure ratio. By measuring the actual combustion chamber pressure, the desired fuel flow is obtained.

Integral rocket-ramjet closed loop fuel control system

In an integral rocket-ramjet having a combustor which initially serves as a rocket combustion chamber for booster propellant, and after the booster propellant is expended, serves as a ramjet combustor where fuel and air are burned, a fuel control system is described for the ramjet stage by which ram burner light-off is automatically initiated upon transition from rocket to ramjet propulsion. The fuel control regulates fuel flow to the combustor over the entire flight regime and responds to operating conditions to provide a light-off schedule, to stabilize the shock wave in the air inlet, to provide a maximum fuel-to-air ratio limit, to limit the maximum vehicle Mach number, and to prevent lean burner blowout by providing a minimum fuel-to-air ratio limit. Mach number limiting is performed in closed loop fashion, while the other functions are scheduled or open loop controls. Fuel flow to combustion chamber pressure ratio is used to provide fuel-to-air ratio limits, actual combustion chamber pressure being measured to provide the desired fuel flow signal.

Integral rocket-ramjet open loop fuel control system

A multi-mode electronic wind turbine control system establishes a reference blade angle for a two-bladed, horizontal axis, variable pitch wind turbine rotor, the blade angle being regulated by a hydraulic pitch change mechanism. The rotor, via appropriate shafts and a gearbox, is coupled to a synchronous generator to produce electrical energy which is fed to a power utility grid. The control system provides closed loop pitch control for rotor acceleration rate during start-up, for rotor deceleration rate during shutdown, for speed control when the synchronous generator is off-line, and for power control when the synchronous generator is on-line. A single control integrator is used for all closed loop operating modes, with a rate limiter circuit in front of the control integrator to prevent integrator overtravel. The integrator has maximum and minimum blade angle stops, the minimum stop being variable as a function of rotor speed and wind speed. When on-line, power control is provided by a unique shaft torque control using proportional plus integral plus derivative controls in combination.

Multi-mode control system for wind turbines

A power generating system includes a wind turbine driven generator, the wind turbine having a wind driven rotor with a plurality of variable pitch angle blades. The blade angle is scheduled during acceleration and deceleration of the wind turbine by open loop controls to minimize stresses, and is scheduled during powered operation by closed loop controls to maintain desired torque or speed. The closed loop controls contain an integrator which produces an integral blade angle control signal. The scheduled blade angle is fed back to the integrators through an integrator tracking network to maintain the integral blade angle control signal at all times within a preselected range relative to the scheduled blade angle.

Wind turbine generator having integrator tracking

Wind energy is used to drive a wind turbine, which is in turn connected to an electrical generator to produce electrical power. The pitch angle of the wind turbine blades is controlled in a closed loop manner to maintain either a constant generator speed for isolated power generating stations or when the generator is synchronized to the load, or constant generator output power or shaft torque when the generator is connected to an electrical grid. Open loop acceleration and deceleration schedules are provided to minimize blade stress and shaft torque variations during start up and shutdown transients, limiting blade angle excursions as a function of wind velocity and speed. The schedules may be implemented either electronically or by a suitably programmed digital computer. The gains in the speed, torque and power loop controls are scheduled as a function of average wind velocity to optimize stability and response. An anticipatory blade angle schedule responsive to instantaneous wind velocity is added to the desired blade angle reference from the closed loop controls to minimize transient excursions in output power or generator speed resulting from wind gusts.

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South Windsor, CT, United States of America

John P Patrick