The Modeling Of Direct-Drive Permanent Magnet Wind Power System And Its Control Strategy In Mircogrid

The environmental degradation and energy shortage have aroused extensive attention, wind generator has become an important source of the electric supply. D-PMSG seems to have a good prospect because of it’s significant technological advantages. In order to solve the contradiction between DG and grid, the microgrid comes into being. This thesis has studied on the modeling, control strategies, LVRT and operating charaeteristies of the D-PMSG, and also the control strategies of DG connects to the mircogrid. The main contents are as follows:(1)This paper constructes and analyzes the mathematical model of wind velocity, aerodynamic, shaft system, and derives the dynamic equations of the permanent magnet synchronous generator expressed in the d-q rotating reference frame.(2)According to vector control principle and feedforward compensation method, this paper designs an integrated control model of D-PMSG, and verifies the accuracy of decoupling control model, MPPT model and pitch control model by simulation.(3)The LVRT capability of D-PMSG is improved both by adding a crowbar circuit with unloading resistance in DC-link and by adding a designed reactive power operation control strategy in grid side converter, and the simulation verification is finished.(4)A new control form of microgrid based on energy storage’s V/f control is suggested:the energy storage adopts V/f control and other DGs adopt PQ control when microgrid works in island mode; the energy storage still adopts V/f control based on local information when micogrid works in grid-connect mode, the control strategies need not to be changed.