초록 ▼

A fault-tolerant control system and method for variable-speed variable-pitch wind turbines with an inverter-fed generator. When generator faults are detected, the generator torque and/or flux is limited to prevent propagation of the faults and possible failure and shutdown of the generator. The cont

A fault-tolerant control system and method for variable-speed variable-pitch wind turbines with an inverter-fed generator. When generator faults are detected, the generator torque and/or flux is limited to prevent propagation of the faults and possible failure and shutdown of the generator. The control system and method improves on two-loop control methods for variable-speed variable-pitch wind turbines and provides improved power delivery under fault conditions.

대표청구항 ▼

1. A method for fault-tolerant control of a wind turbine including a generator and a generator monitoring subsystem which continuously senses the condition of the generator and provides to the fault-tolerant control system fault management parameters, either as reduced time derivative of stator flux

1. A method for fault-tolerant control of a wind turbine including a generator and a generator monitoring subsystem which continuously senses the condition of the generator and provides to the fault-tolerant control system fault management parameters, either as reduced time derivative of stator flux linkage in a faulty stator phase wherein the magnitude of the rotating magnetic flux and/or the magnitude of the torque building current is manipulated in such a way that time derivative of stator flux linkage is kept below the given reduced value at the fault location, or as fault localizing angles θ1, θ2 and the maximum allowed torque Tgf at the fault location on the generator magnetic flux circumference wherein said method reduces magnitude Tg of the generator torque locally around the fault location such that the fault does not further progress and the energy production is deteriorated as less as possible, said method comprising the following steps: if no generator fault condition is detected, operating said wind turbine in a normal state; andif a generator fault condition is detected, carrying out the steps of: (1) acquisition of the momentary angular velocity of the generator ωg and the associated required generator torque T′gref and providing fault management parameters θ1, θ2, Tgf corresponding to said detected fault;(2) control system decides what is the higher value of the torque Tg—nonf necessary to maintain unchanged average torque and angular velocity of the generator;(3) the value Tg—nonf is capped to the nominal torque value T, and the torque modulation angles θon, θoff are computed;(4) computing the angle value θstart needed for torque modulation and setting Tg—nonf to Tg* if the difference between θon and θoff is greater than π;(5) setting the angle value θend needed for torque modulation;(6) performing torque modulation based on values Tgf, Tg—nonf, θstart and end such that the torque is maintained at the fault location on the value Tgf while at the remaining part of the generator magnetic flux circumference the torque Tg is maintained such that the average torque value Tav is on the required level;(7) computing the generator speed value ωg1 and setting wind turbine speed reference ωref of the wind turbine speed control system accordingly, wherein the wind turbine operation is feasible if generator speed value ωg1 is greater than the generator cut-in speed. 2. The method according to claim 1 wherein said fault-tolerant control system comprises a first control loop—slow loop and a second control loop—fast loop nested within said first control loop, said first control loop controlling turbine blade pitch angle β, and said second control loop controlling generator torque Tg. 3. The method according to claim 1 wherein said detected generator fault condition is caused by a defect in a stator of the generator of said wind turbine. 4. The method according to claim 3 wherein said defect is located in a region bounded by two planes that intersect along the axis of said stator, said planes forming an angle at said axis. 5. The method according to claim 1 wherein said detected generator fault is caused by a defect in a rotor of the generator of said wind turbine. 6. The method according to claim 5 wherein said defect is located in a region bounded by two planes that intersect along the axis of said rotor, said planes forming an angle at said axis. 7. The method according to claim 1 wherein said generator is a synchronous generator. 8. The method according to claim 1 wherein said generator is an induction generator. 9. A method for fault-tolerant control of a wind turbine including a generator and a generator monitoring subsystem which continuously senses the condition of the generator and provides to a fault-tolerant control system fault management parameters in terms of faulty stator phase and the maximum allowed derivative of the stator fux linkage in the faulty stator phase, wherein said method manipulates the magnitude of the rotating magnetic flux in the stator and/or the magnitude of the torque building current in such a way that time derivative of stator flux linkage is kept below the maximum allowed value at the fault location. 10. The method according to claim 9 wherein said generator is a synchronous generator. 11. The method according to claim 9 wherein said generator is an induction generator. 12. A wind turbine system including: a generator;a generator monitoring subsystem having sensors for continuously sensing either maximum allowed stator flux linkage time derivative in a faulty phase or fault localizing angles θ1, θ2 and the maximum allowed torque Tgf at the fault location on the generator magnetic flux circumference; a control system controlling a magnitude of a rotating magnetic flux in the stator and/or a magnitude of a torque building current such that either a time derivative of stator flux linkage or the magnitude Tg of the generator torque are less than the maximum allowed values at the fault location. 13. The wind turbine system of claim 12, wherein said generator is a synchronous generator. 14. The wind turbine system of claim 12, wherein said generator is an induction generator.