GENERATOR-FAULT-TOLERANT CONTROL FOR A VARIABLE-SPEED VARIABLE-PITCH WIND TURBINE

摘要

Present invention relates to a fault-tolerant control scheme for variable-speed variable-pitch wind turbines with an inverter-fed generator. Invention is focused on generator faults that can be well characterized with machine flux path areas where the generator torque should be limited to prevent fault propagation and with the maximum safety torque value in that path areas. An extension of the classical two-loop control structure of variable-speed variable-pitch wind turbines is proposed which ensures that the fault is fully respected in operation and that power delivery under fault is deteriorated as less as possible compared to healthy machine conditions. The first step is the acquisition of the momentary angular velocity of the generator cog and the associated required generator torque T'_gref (401). Upon detection of a fault, the fault detection algorithm establishes the location of the fault and the fault severity providing the location in terms of angles θ₁, θ₂ related to the rotating magnetic flux frame, and the maximum allowed torque T_gf at the fault location (step 402). It is understood that the fault may occur on the stator or the rotor of the generator. In the fault-managed state, the generator torque will be modulated to exhibit reduced torque T_gf around the location of the fault and an increased torque T _{g_nonf} in all other areas of the circumference of the rotating magnetic flux.