The Sensorless Control Technique Of Direct-drive Wind Generators

Direct drive wind turbine becomes an important research direction after DFIG in the field of wind power, because of its high energy conversion efficiency, high reliability, and flexible network power control, etc. In MW direct drive system, due to the position encoders'installation difficulties and other reasons, sensorless control of permanent magnet direct-drive technology becomes a research hotspot in wind power. Therefore, the sensorless control technology of the direct-drive PMSG is focused on in this paper, meanwhile the theoretical research on the stator flux observer design method and control strategy are discussed and analysed. In addition, the correctness of theoretical results is fully confirmed through the simulations and experiments.First, the wind power generation situation and development trend are introduced, and then, two ways of wind power speed control, CSCF and VSCF, are expounded. On this basis, the active and passive rectifier rectifiers are compared. Then, the research status quo of the sensorless control technology of PMSM is described.Second, PMSG and its control technology are researched. Based on the coordinate system arranged, the coordinate transformation matrix and various coordinates PMSG mathematical model are derived. Then the PMSG vector control methods are researched and compared deeply to get the ZDAC control block diagram.Third, the sensorless control technology of PMSG is deeply studied. From the simulation comparison of several stator flux observers based on the U-I mode, the integrators with saturation-fed based on axis transform are selected. Meanwhile, the selection principles of the relevant parameters and the compensation of rotor position are discussed.Fourth, as a result of theoretical simulation and verification, the sensorless vector control system simulation model of the direct-drive PMSG is built. The rotor position estimation accuracy, ZDAC control accuracy, rotor position and phase current phase relationship are analyzed and verified.Finally, the experiment platform of PMSM is built to simulate the operation of wind power state. The system hardware and software based on DSP are designed. Through the low power generation experiments, the sensorless control technology based on the flux observe and the vector strategy mentioned in this paper are verified.