Influence Of Different Faults On Power Grid-Connected Permanent Magnet Half Direct-direct Wind Turbine

Wind power is an important part of the new energy. Nowadays, the installed capacity of wind turbines of China has become the largest in both total installed capacity and new power capacity in the world. Permanent magnet half direct-drive wind turbine has combined the advantages of doubly-fed wind power generator and direct-drive permanent magnet wind turbine, which will contribute to the development of wind power in the future. Half direct-drive permanent magnet wind turbine is the core component of wind power grid and it tends to have open circuit fault, excitation-loss fault or short-circuit fault when affected by high temperature or vibration in the operation process. Meanwhile, generators often run under different wind speed because of the randomness and intermittent of wind power. Therefore, the Post-fault behavior in permanent magnet half direct-drive wind turbine under different wind speed is accurately computed and the key characteristics of that can be used in on-line monitoring and diagnosis faults system, which has very important realistic meaning.Thesis, the permanent magnet half direct-drive wind turbine with 1.5MW,32 poles was investigated. Based on the theory of electromagnetic field, the two-dimensional field-circuit coupling model was established and the characteristic quantities with open circuit fault, short circuit fault, and demagnetization fault were researched. Firstly, the calculation of the phase voltage, phase current of the motor, the air-gap magnetic field and electromagnetic with branch open circuit fault, and single-phase circuit fault under rated speed were analyzed. On this basis, the influence of the single-phase circuit fault of generator under different wind speeds was researched. Then, the phase current and torque were studied with three phase short circuit fault and single-phase grounding fault under rated speed. The phase current in three phase short circuit fault with different wind speeds was analyzed. Then the branch current, flux leakage coefficient, and pole-arc coefficient with demagnetization fault in different positions of one unit structure under rated wind speed were calculated. Meanwhile, for example as the demagnetization fault, the electromagnetic field under different wind speed was studied. Considering that the relay device didn’t removal of the generator after demagnetization fault, the demagnetization complex open circuit fault and demagnetization complex short circuit fault may occur.In order to verify the correctness and rationality of the calculation method, this paper uses the method to simulate and compute the single block permanent magnet demagnetization fault of a similar structure of small permanent magnet wind turbine. By comparing to the experimental results, the simulation results presents a reasonable error. In conclusion, the study different fault condition on the effects of parameters such as current, voltage generator, and electromagnetic torque is beneficial for human life, which will provide a reference for on-line monitoring and fault diagnosis.