United Technologies Corporation

Kermit I Harner

John P Patrick

Joseph M Kos

Roy W Schneider

Charles F Stearns

Robert Sherman

Glidden S Doman

Frank R Niessen

Mark L Harris

Kenneth F Vosseller

Henry S Healy

Eugene D DiValentin

William W Hixson

Michael A Spadafora

A variable speed wind turbine includes a frequency converter which converts variable frequency AC from a turbine driven AC generator to fixed frequency AC for delivery to a power grid. The frequency converter is typically an electronic cycloconverter or rectifier-inverter and is also used to control the power flow from the AC generator to the grid which thereby controls the air gap torque between the generator stator and rotor. The turbine speed is maneuvered to increase efficiency by precisely controlling the air gap torque according to a schedule defining sensed generator speed versus sensed generated power.

Variable speed wind turbine

A blade pitch angle control system for a wind turbine includes an improved control means (95) for providing a minimum pitch angle reference signal indicative of desired blade pitch at wind velocities less than rated. The control means includes means (35 and 30) for providing signals indicative of generated (output) power or torque and the rotational frequency of the wind turbine rotor. The output and rotor speed signals are input to a function generator which, in response to such signals, provides a signal indicative of the minimum pitch angle.

Blade pitch angle control for large wind turbines

An improved slave propeller synchrophaser (10) includes a first control (14) responsive to a phase difference signal (28) and a phase difference reference signal (26) for providing a phase error signal (112) and for providing a propeller speed reference bias signal (40) for a speed governor (46), and also includes, according to the present invention, a second control (12) responsive to the phase error signal (112) for providing an engine power reference bias signal (80) for an engine power control for providing a very limited amount of propeller fine speed control within the dead band of the propeller speed governor while at the same time substantially maintaining engine power at the commanded power level.

Propeller synchrophaser

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

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 turbine driven rotor with a variable pitch angle blade. Stresses on the system during startup and shutdown are minimized by scheduling the blade angle as a function of the rotor speed and wind velocity to provide a minimum blade angle relative to the fully powered blade angle during rotor acceleration, and to provide a minimum blade angle relative to the fully powered blade angle during rotor deceleration.

Wind turbine generator acceleration control

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.

Wind turbine generator pitch control system

This invention relates to an improved surge control for a gas turbine type of power plant that bleeds the compressor to avoid surge and serves to isolate the effect that the engine area change has on the compressor discharge pressure rate signal to effectuate a viable signal indicative solely of acceleration and deceleration.

Compressor bleed sensor and control for turbine type power plants

A coordinated fan pitch, fuel flow and fan exhaust nozzle area control for a gas turbine powered aircraft propulsor of the bypass duct, variable pitch and exhaust nozzle configuration serves to effectuate reverse pitch change through feather, by minimizing forward thrust excursion and shaft torque to obtain rapid reverse thrust response.

Control system for variable pitch fan propulsor with reverse pitch

A control for a variable pitch fan propulsor driven by a turbine type of power plant which fan is mounted in an engine bypass duct having a variable exit nozzle. The control serves to coordinate the control of fuel flow to the engine, the area of the fan exit nozzle, and the pitch of the fan blades by biasing the power lever position signal with Flight Mach No. An additional feature is the inclusion of fan surge control derived from signals of flight Mach No. and corrected free turbine speed.

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Windsor, CT, United States of America

Kermit I Harner