Generator-fault-tolerant control for a variable-speed variable-pitch wind turbine

摘要

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.

主权项

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; and if 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.