183 results about "Tip-speed ratio" patented technology

Wind turbine with a rotor blade relatively insensitive to turbulence because it is more slender than prior blades and is nevertheless able to generate sufficient lift by virtue of the fact that flow enhancing elements such as vortex generators combat flow separation. The slenderness is defined by the chord numbers C and D of which C is defined as C=Ncrclrλ2 / R2, in which N is the number of blades, cr is the local chord, cl the lift coefficient, r the radial position, λ the tip speed ratio and R the rotor radius. Subsequently, the chord should be less than what follows from the equation C=M in which M=−1.19+9.74Cp−21.01Cp2+17.50Cp3 and Cp is the power coefficient. This wind turbine is subject to about 2-12% less operational loads and to about 5-40% reduced survival wind speed loads compared to classical designs.

A turbine (2) driven electric power production system (1), —said turbine (2) arranged for being driven by a fluid (3) having a fluid speed (v) varying in time, —said turbine (2) connected to a hydrostatic displacement pump (6) further connected to a hydrostatic displacement motor (8) as part of a closed loop hydrostatic transmission system (7), —said motor (8) arranged for driving an electrical generator (9) supplying AC power (10) at a frequency (fg) near a given desired frequency (fdes), characterized by a closed loop system arranged for controlling a volumetric displacement (13) of the hydrostatic motor (8), comprising —a fluid speed meter (11m) arranged for producing a speed signal (11s) representing a speed (v) of said fluid (3), and —a rotational speed meter (12m) arranged for providing a rotational speed signal (12s) representing a rotational speed measurement (ω) of said turbine (2), —a motor displacement control system (15) for continuously receiving said speed signal (11s) and said rotational speed signal (12s) and arranged for calculating a control signal (16), —a volumetric displacement control actuator (17) on said hydrostatic motor, arranged for receiving said control signal (16) for continuously adjusting a volumetric displacement (d) of said hydrostatic motor (8) for maintaining a set turbine tip speed ratio (tsrset) and thereby providing an improved power efficiency of the power production system (1) during fluctuations in said fluid speed (v).

The invention belongs to the technical field of source network coordination and relates to a method for enabling a fan operating at a low speed to be adjusted to operate at an optimum tip speed ratio and simultaneously and automatically correcting the optimum tip speed ratio regularly. The method includes the following steps: calculating an accurate power value of a power generator according to feedback torque and rotating speed; calculating wind speed according to power factors corresponding to the power and the optimum tip speed ratio; when the rotating speed can be adjusted, adjusting the rotating speed to enable the fan to operate in an optimum tip speed ratio state; when the rotating speed cannot be adjusted, adjusting a pitch angle to enable the fan to operate in an optimum tip speed ratio state; and adopting a statistical average hill-climbing method to correct the optimum tip speed ratio corresponding to a minimum pitch angle. By adopting the method, problems of existing methods are solved.

In a fluid power generator system using operative fluid energy, a measured tip speed ratio and a reference tip speed ratio are compared with each other. If the measured tip speed ratio is smaller than the reference tip speed ratio, a generator is placed in a no-load state, thereby restoring the number of rotations of the wing axial shaft to the number of rotations corresponding to the reference tip speed ratio. Further, the operation of the generator is controlled on the basis of the tip speed ratio calculated from the flow rate of the fluid, thereby providing a maximum output for each flow rate. In this way, a change in the flow rate and number of rotations can be appropriately dealt with and the maximum output for each flow rate of the operative fluid can be dealt with, thereby increasing a quantity of generated power.

Wind turbine with a rotor blade relatively insensitive to turbulence because it is more slender than prior blades and is nevertheless able to generate sufficient lift by virtue of the fact that flow enhancing elements such as vortex generators combat flow separation. The slenderness is defined by the chord numbers C and D of which C is defined as C=Ncrclrλ2 / R2, in which N is the number of blades, cr is the local chord, cl the lift coefficient, r the radial position, λ the tip speed ratio and R the rotor radius. Subsequently, the chord should be less than what follows from the equation C=M in which M=−1.19+9.74Cp−21.01Cp2+17.50Cp3 and Cp is the power coefficient. This wind turbine is subject to about 2-12% less operational loads and to about 5-40% reduced survival wind speed loads compared to classical designs.

A method for operating a wind turbine is disclosed. The wind turbine comprises a rotor having a set of wind turbine blades, said rotor being mounted on a tower. The method comprises the steps of: Providing a curve defining optimal pitch angle as a function of tip speed ratio for the wind turbine blades or as a function of wind speed. Modifying at least a part of said optimal pitch angle curve by applying a safety buffer, e.g. at tip speed ratios and / or pitch angles where there is a risk that the blades may stall and / or that overload is caused to the wind turbine, thereby obtaining a safety modified pitch angle curve. Operating the wind turbine in accordance with the safety modified pitch angle curve. Measuring one or more parameters providing information regarding wind conditions and / or loads on one or more components of the wind turbine, during operation of the wind turbine. Adjusting the safety buffer, based on said measurements, thereby obtaining an adjusted pitch angle curve, and operating the wind turbine in accordance with the adjusted pitch angle curve. The safety buffer is applied in order to ensure that the blades of the wind turbine do not stall and / or that the wind turbine is not overloaded, but it has the effect that the wind turbine is operated in a suboptimal manner from an energy production view. Since the safety buffer is adjusted based on measured parameters, it can be reduced if it is detected that the actual operating conditions are less severe than expected. This allows the wind turbine to be operated in a more optimal manner, thereby increasing the energy production of the wind turbine.

The invention discloses a full-wind-speed frequency response control method for a doubly-fed wind generator. According to the method, frequency response control can be conducted by actively identifying wind speed intervals and modifying a drooping coefficient in a self-adaptive mode. Firstly, the relation between the load shedding rate and the suboptimum tip speed ratio of the doubly-fed wind generator is established according to a doubly-fed wind power unit characteristic curve given by a manufacturer; a full wind speed is divided into a first wind speed interval, a second wind speed interval, a third wind speed interval and a fourth wind speed interval according to the wind speed from low to high; the division criterion of the four wind speed intervals is updated online according to the current load shedding rate of the doubly-fed wind generator; when the real-time frequency of a system is lowered and exceeds a set dead zone threshold, the wind speed intervals are identified according to collected real-time wind speed signals; real-time unit spare capacity is calculated, the drooping coefficient is modified in the self-adaptive mode, and then frequency response control is completed. By means of the method, the frequency response capability of the medium-wind-speed interval and the high-wind-speed interval can be improved, and the rotating speed of the generator in the weak-wind interval and the low-wind-speed interval can be not lower than the minimum allowed rotating speed.

A method and a system for managing loads on a wind turbine are provided. The method includes receiving a signal relative to a yaw misalignment of the wind turbine, generating a yaw error signal based on the yaw misalignment, and comparing the yaw error signal to a first predetermined yaw error threshold value. The method also includes regulating a speed of the rotor to a value determined by a predetermined tip speed ratio, reducing the yaw misalignment using a yaw control system, and restarting the wind turbine if the yaw error signal is reduced to less than a second predetermined yaw error threshold value within a predetermined period of time. The method further includes shutting down the wind turbine if the yaw error signal remains greater than the second predetermined yaw error threshold value beyond the predetermined period of time.

The invention discloses a method for identifying and setting parameters of a wind generating set controller, and belongs to the technical field of control over a wind generating set. The method comprises the steps that a Bladed software model is utilized for being linearly combined with a model order reduction algorithm to build a unit linear model suitable for setting the parameters; and then, according to the wind speed distribution probability of a wind field, optimal setting and comprehensive calculation of PI parameters of the controller are carried out, and on the basis of a parameter identifying result of Bladed software, an optimum rotary speed-torque control gain coefficient and a gain factor in self-adaptation variable pitch control are calculated. Identifying of related parameters such as a largest wind energy utilization coefficient, an optimum tip-speed ratio and an optimal propeller pitch angle is carried out according to a Bladed simulation model built according to unit equipment parameters, and the important prerequisite condition is provided for control over maximal wind energy capture of the unit is provided; the self-adaptation variable pitch control is achieved, and the robustness of a common PI variable pitch controller is improved; and the guidance is provided for design and optimization of the controller, and the method has the higher practical and reference value.

The invention relates to a maximum power point tracking method of a wind generating set. The method includes: calculating rotor power coefficient Cp and then calculating a blade top speed ratio Lambda as well as dCp / d Lambda; when dCp / d Lambda is greater than zero, an actual working point is at the left side of a maximum rotor power coefficient point, the blade top speed ratio of a wind turbine is less than the optimal blade top speed ratio, the rotating speed of the blade is increased; when dCp / d Lambda is less than zero, the actual working point is at the right side of the maximum rotor power coefficient point, the blade top speed ratio of the wind turbine is more than the optimal blade top speed ratio, the rotating speed of the blade is reduced; when dCp / d Lambda is equal to zero, the actual working point is at the maximum rotor power coefficient point, the actual blade top speed ratio of the wind turbine is equal to the optimal blade top speed ratio; the wind turbine runs at an optimal state; the optimal rotating speed and the actual rotating speed of the wind turbine is subtracted; the difference value is converted into a control current id<*> by the control of PI current; difference value of the id<*> and the actual current id of the wind generating set is calculated and input into PWM for modulating; simultaneously the difference value of 0 and the actual current iq of the wind generating is input into the PWM for modulating; the modulating result controls a drive circuit to realize the maximum power point tracking.

The present invention relates to a method of controlling the aerodynamic load of a wind turbine blade by controlling the tip speed ratio (TSR) and / or blade pitch setting of the wind turbine blade so as to optimize power production. A wind turbine blade undergoes an aero-elastic response including deflection and twist that is a function of the blade loading. The blade loading is dependent on the wind speed, TSR, and pitch setting. The aero-elastic response requires a different TSR and / or pitch to be selected throughout the power curve in order to maintain the optimum power production and to improve energy capture.

Wind turbines and methods for controlling wind turbine loading are provided. In one embodiment, a method includes the steps of determining a current wind speed. The method further includes determining a tip speed ratio and a pitch angle that maximize a power coefficient under at least one of the following conditions: a thrust value is less than or equal to a pre-established maximum thrust, a generator speed value is less than or equal to a pre-established maximum generator speed, or a generator torque is less than or equal to a pre-established maximum generator torque. The method further includes calculating a desired generator speed value based on the current wind speed and a tip speed ratio. The method further includes calculating a desired generator power value based on the desired generator speed value.

The invention relates to a neural network compensation control method for capturing maximum wind energy in a wind power system. The neural network compensation control method includes a, acquiring the speed of the wind, and acquiring a reference value of the speed of a wind turbine and a corresponding disturbance speed of the wind turbine according to the wind speed, a reference value of a tip speed ratio and a gear ratio of a gear box; b, acquiring a speed error according to the reference value of the speed of the wind turbine and a speed value of the wind turbine, adopting the PID closed-loop regulation on the reference value of the speed of the wind turbine and the speed error, and acquiring a reference value of the steady torque of the wind turbine; c, adopting the reference value of the steady torque of the wind turbine and the disturbance speed of the wind turbine as the input of the the BP neural network, adopting the PSO (particle swarm optimization)algorithm to train until a required torque control value of the wind turbine is outputted, and accordingly controlling the torque of the wind torque through the torque control value of the wind turbine. By the aid of the neural network compensation control method, effective control of the torque of the wind turbine is realized, cost is reduced, adapting range is wide, and the neural network compensation control method is safe and reliable.

The invention relates to a vertical shaft wind turbine with lifting power and resistance complementary adjustment, which comprises a lifting power type vane, a resistance type vane, a support, a rotary shaft and a resistance type vane adjusting mechanism, wherein the adjusting mechanism is used for adjusting the position of the resistance type vane in the radical direction of the rotary shaft of the wind turbine or the windward side angle of the resistance type vane. By adjusting the position and the angle of the resistance type vane in the integral structure of the wind turbine, the optimal adjustment for the tip speed ratio Lambada of the vertical shaft wind turbine is simply and easily realized, the rated wind speed of the wind turbine can be designed or adjusted according to the actual wind speed and density of a wind field so that the wind turbine reaches the optimal wind energy collecting efficiency under a rated wind speed, the problem of low wind speed start of the wind turbine is solved, simultaneously the upper limit of wind energy and wind speed connection of the lifting power type vane is also improved, and the wind speed range of the wind turbine is further expanded so that the utilization rate of the wind energy is further improved; and besides, the damages and influences of super-high wind speeds (wind damages) to the wind turbine are also effectively reduced.

A turbine (2) driven electric power production system (1), - said turbine (2) arranged for being driven by a fluid (3) having a fluid speed (v) varying in time, - said turbine (2) connected to a hydrostatic displacement pump (6) further connected to a hydrostatic displacement motor (8) as part of a closed loop hydrostatic transmission system (7), - said motor (8) arranged for driving an electrical generator (9) supplying AC power (10) at a frequency (fg) near a given desired frequency (fdes), characterized by a closed loop system arranged for controlling a volumetric displacement (13) of the hydrostatic motor (8), comprising - a fluid speed meter (11m) arranged for producing a speed signal (11s) representing a speed (v) of said fluid (3), and - a rotational speed meter (12m) arranged for providing a rotational speed signal (12s) representing a rotational speed measurement (); of said turbine (2), - a motor displacement control system (15) for continuously receiving said speed signal (11s) and said rotational speed signal (12s) and arranged for calculating a control signal (16), - a volumetric displacement control actuator (17) on said hydrostatic motor, arranged for receiving said control signal (16) for continuously adjusting a volumetric displacement (d) of said hydrostatic motor (8) for maintaining a set turbine tip speed ratio (tsrset) and thereby providing an improved power efficiency of the power production system (1) during fluctuations in said fluid speed (v).

The present invention discloses an extremum seeking-based control method for maximum output tracking of a wind turbine generator, mainly comprising three steps of first closed-loop feedback, second closed-loop feedback, and third closed-loop feedback. The method for resisting mechanical fatigue of a double-fed variable speed constant frequency wind turbine generator by controlling mechanical torque while capturing maximum wind energy provided in the present invention is applied to a double-fed variable speed constant frequency wind turbine system by improving the control based on sliding mode extremum seeking with the following effects that, with regard to the maximum wind energy tracking effect, the rotating speed can be quickly adjusted to keep the tip speed ratio λ as its optimum value after the wind speed changes, so that the wind energy utilization coefficient is restored to the maximum value.

The invention discloses a load modelling method and a load control method for a wind turbine generator system. The load modelling method and the load control method for the wind turbine generator system comprise the following steps: firstly, acquiring axial inducing factors and circumferential inducing factors corresponding to each group of tip speed ratios and pitch angles through iterating; secondly, calculating flapping coefficients and wind energy coefficients; thirdly, performing nonlinear fitting through the flapping coefficients and the wind energy coefficients corresponding to a plurality of groups of tip speed ratios and pitch angles to obtain a calculating formula of the flapping coefficients and the wind energy coefficients with respect to the tip speed ratios and the pitch angles, and obtaining a load model; fourthly, on the basis of the load model, calculating an optimal pitch angle corresponding to the least flapping load at each wind speed when the output is constant, and performing nonlinear fitting to obtain a formula of the optimal pitch angle with respect to the wind speed; fifthly, obtaining the optimal pitch angles according to the wind speeds when the wind turbine generator system operates through calculating, and obtaining pitch angle adjustment values; and finally, superposing the pitch angle adjustment values obtained on the basis of a PID (Proportion Integration Differentiation) variable pitch control method, and performing pitch angle control. According to the load modelling method and the load control method for the wind turbine generator system, shimmy load and flipping load are comprehensively taken into consideration, and a more accurate load model and a more accurate load control method are realized.

The invention provides a method and a system for determining a blade control parameter of a variable speed and variable pitch wind generating set. The method comprises the following steps: monitoring current set power of a target variable speed and variable pitch wind generating set in real time; determining a curve between a wind power utilization coefficient and a tip speed ratio of the target variable speed and variable pitch wind generating set; determining an intersection point between the wind power utilization coefficient and the tip speed ratio corresponding to different pitch angles and a set power value at current air density corresponding to the intersection point; when the monitored current set power meets a set power set value, determining a minimum pitch angle corresponding to the current set power under the condition of avoiding blade stall; when the current set power is within the range of two set power set values, determining the minimum pitch angle corresponding to the current set power under the condition of avoiding blade stall by using an interpolation method. The purposes of avoiding the blade stall and improving the set operation stability and the power generation under the condition that the original design of the set is not changed can be achieved.

The invention relates to an optimal control method capable of adapting to air density changes of the environment of a wind generator set. The method comprises the following steps that according to the altitude of a wind field area, the height of a fan hub and actually-measured environment temperature outside a cabin, actual air density of the height of the center of a hub of a wind generation set is calculated, and according to calculated torque correction coefficients relative to the standard air density, an actual generator control torque is corrected, and therefore the rotating of a wind wheel is affected, and the set can be always maintained in the optimum tip-speed ratio to run under the different air density conditions; and the problem that a fan runs under the non-standard air density and deviates from the optimum control curve is solved, the maximum electricity generating efficiency output can be dynamically obtained in real time, and the adaptation of the wind generator set to different environments of different areas is improved.

The invention provides a power tracking method of a wind power generation system free of a wind speed sensor. The method comprises following steps: a motion equation of the maximum power tracking control of the wind power generation system is established; iterative optimization is performed on output power and rotor speed at the variable wind speed with the adoption of a variable step size algorithm, the maximum power point is tracked, and the optimal tip speed ratio is obtained by calculation; a fuzzy controller is adopted as a power controller, errors and error change rate of the tip speed ratio are taken as input, variable quantity of stator side regulation voltage is taken as output, a fuzzy rule is formulated, the output of the fuzzy controller is subjected to ambiguity resolution operation, and the corresponding accurate variable is obtained; the rotating speed of an electric generator is adjusted according to the variable quantity of stator side regulation voltage, control tracking for the rotor speed of the wind power generation system is realized, and the maximum power of the wind power generation system is tracked; adverse effects on output power of the wind power generation system under the conditions of inaccurate wind speed measurement and lagged wind speed measurement are avoided.

The invention provides a self-adaption maximum power tracing control method of a power generating set. First, the reference tip speed ratio and reference power coefficient of the to-be-tested power generating set are set, so that a reference rotate speed torque tracking curve and a deformation curve can be obtained according to the reference tip speed ratio and reference power coefficient. Then a section between a cut-in wind speed and a rated wind speed is divided into small sections. The power generating set runs according to the deformation curve corresponding to a deformation coefficient in a tracing manner. After each operation period, result data such as output power in the period are measured and subjected to statistical averaging. Therefore, during constant operation, the deformation coefficient is an optimization variable and the output power is an optimization object, the optimal deformation coefficient is sought through a method of optimization, so that the output power of the power generating set becomes the maximum. Finally, after long term operation of the power generating set, the optimal rotate speed torque tracking curve in the whole operation wind speed range can be obtained by connecting segments of the deformation curves determined according to deformation coefficients of each wind speed section.

A system and a method for controlling operation of an underwater power generator is described, as well as computing componentry for controlling the operation of the underwater power generator. The system comprises: meters for measuring selected properties associated with blade speed and inward water flow of the underwater power generator; a drive for altering one or more selected aspects of operation of the underwater power generator; and a data processing apparatus comprising a central processing unit (CPU), a memory operatively connected to the CPU, the memory containing a program adapted to be executed by the CPU, wherein the CPU and / or memory are operatively adapted to receive information from the meters to calculate a Tip Speed Ratio (TSR or λ) and implement an instruction to the drive to change the one or more selected operating parameters of the underwater power generator in response to the calculated TSR or λ.

The invention discloses a megawatt wind power generation master control system, which comprises a master control unit, an upper monitoring system, a pitch control system and a variable frequency system, wherein the master control unit consists of a tower-bottom control cabinet and a cabin control cabinet; the tower-bottom control cabinet is provided with a master control central processing unit (CPU) module, a remote input output (IO) extended optical fiber master module, a CANOpen communication master module, an RS232 expansion module, a tower-bottom universal IO module, a first multimode optical fiber port four-electrical port industrial switch, a single-mode photoelectric converter, a first pigtail box, an in-situ upper computer and multimode optical fibers; and the master control unit is connected with the upper monitoring system through the single-mode photoelectric converter, connected with the variable frequency system through the CANOpen communication master module and connected with the pitch control system through an RS485 module. In the megawatt wind power generation master control system, the characteristics of a wind machine are taken as bases, and when the wind machine runs at an optimal tip-speed ratio lambda, a fan unit captures maximum energy to maintain the stable output power of a generator.

The invention provides an optimum tip speed ratio control method and device under variable air densities. The method comprises the steps of obtaining the actual air density of the position where a wind generating set is located, calculating the target rotating speed of the wind generating set under the actual air density at a transition area between an area II and an area III, obtaining the rotating speed and torque control reference value corresponding to the optimum tip speed ratio of the wind generating set under the actual air density, and using the target rotating speed, the rotating speed and torque control reference value and the measured rotating speed of wind wheels of the wind generating set as input to carry out optimum tip speed ratio rotating speed and torque control over the wind generating set so as to adjust the rotating speed of the wind wheels of the wind generating set, enable the optimum tip speed ratio sections of the wind generating set under the actual air density and under standard air density to be identical, and further avoid the problems that the optimum tip speed ratio control area is reduced due to changes of air density, the wind-power utilization coefficient is lowered, and the output power of the wind generating set is lowered.

The invention relates to a pitch control method of a variable-speed constant-frequency wind driven power generator at a rated revolution speed stage. The pitch control method comprises the following steps: A. solving Cp-Lambda curves of the wind driven power generator corresponding to different pitch angles; B. finding out the maximal outer envelope line Cpmax-Lambda of a Cp-Lambda curve family and blade pitch angles corresponding to different blade tip speed ratios; C. solving the blade tip speed ratio for the operation of the wind driven power generator according to the incoming wind speed at the rated revolution speed stage; and D. adjusting the blade pitch angle according to the blade tip speed ratio, thus the wind driven power generator operates on the outer envelope line of the Cp-Lambda curve family. According to the invention, optimal power can be ensured for the variable-speed constant-frequency wind driven power generator at the rated revolution speed stage, thus more wind energy can be converted; under the low altitude, the power generation amount can be improved to a certain extent; and under the high altitude, the electricity generation power is improved greatly, the wind wheel load can be reduced greatly, the safety and reliability for the operation of the wind driven power generator are improved, and the variable-speed constant-frequency wind driven power generator at the rated revolution speed stage has important engineering significance.

A low Reynolds number airfoil for a wind turbine blade, the airfoil having a leading edge 101, a trailing edge spaced from the leading edge 101, a chord 120 defined as a straight line joining the leading edge 101 and the trailing edge, a chord 120 length defined as distance between the trailing edge and the point on the leading edge 101 where the chord 120 intersects the leading edge 101 wherein the airfoil comprises a camber 121 between 5% to 7% of the chord 120 length, the camber 121 is disposed within a distance of 17% of the chord 120 length from the leading edge 101 and a thickness of the airfoil not greater than 7% of the chord 120 length. In an embodiment, it discloses A method of designing blade for low wind speed turbine for a site location, the method comprising obtaining time series data for the site location, computing a Weibull shape factor (K) and scale factor (C)corresponding to a Weibull distribution function based on the time series data for the site location, using K and C to identify energy intensive wind speed at the site location, determining blade length based on the energy intensive wind speed, K, C, a design power (PD) of the turbine, a design power coefficient (Cpd), and a density of the air (Ro), wherein the rated power of the turbine depends on load to be connected of the turbine, selecting a generator for use with the turbine, computing a design tip speed ratio based on a rated speed of the generator (NGD), a gear ratio (GR), the design power (PD), K, and C, identifying number of blades (B) depending on the design tip speed ratio and an end-use of the power being produced by the turbine; and identifying a chord 120 length and twist of the blade from root-to-tip.

The invention relates to a method for operating a marine current power plant, comprising a water turbine with several rotor blades arranged as buoyancy rotors, an electric generator which is driven at least indirectly by the water turbine, wherein the water turbine is guided for power limitation in an overspeed range above a power-optimal tip speed ratio. The water turbine is adjusted to the immersion depth of the marine current power plant in such a way that cavitation occurs on at least one rotor blade section in the overspeed range from a cavitation tip speed ratio threshold which lies below a tip speed ratio associated with a runaway speed, and the water turbine is operated for load limitation at tip speed ratios which lie above the cavitation tip speed ratio threshold.

A method and a system for managing loads on a wind turbine are provided. The method includes receiving a signal relative to a yaw misalignment of the wind turbine, generating a yaw error signal based on the yaw misalignment, and comparing the yaw error signal to a first predetermined yaw error threshold value. The method also includes regulating a speed of the rotor to a value determined by a predetermined tip speed ratio, reducing the yaw misalignment using a yaw control system, and restarting the wind turbine if the yaw error signal is reduced to less than a second predetermined yaw error threshold value within a predetermined period of time. The method further includes shutting down the wind turbine if the yaw error signal remains greater than the second predetermined yaw error threshold value beyond the predetermined period of time.

A tidal flow turbine system has a rotor and turbine blades attached at a fixed attitude with respect to the rotor and extending outwardly from the rotor. The stagger angle of the blades, tip speed ratio, or other blade parameters is such that over the in-service operational speed range of the turbine, over a lower range of rotational or tidal flow speeds, increased speed results in increased axial loading on the turbine, but at higher speed range above a predetermined threshold, axial loading on the turbine does not increase.