Control Strategy For Three-level Direct-drive Wind Power System With Pmsg Based On Direct Power Controland Fault-tolerant Control

As a kind of clean energy, wind power has become one of the most development value energy since it is inexhaustible, has large total storage capacity and does not emit environmentally harmful substances in exploitation process. The direct-drive wind turbine without increasing gearbox because of its low rotational speed, low cost and low noise has become the mainstream model of wind power generation.This paper researches on three-level permanent magnet direct drive wind power grid system. Direct power control strategy of three-level converter was studied.Firstly, in this paper the characteristics of the wind turbine and establishes mathematical models of wind machine and permanent magnet synchronous generator is introduced. This paper uses diode clamped three-level converter structure and SVPWM modulation algorithm. The traditional SVPWM control algorithm and the SVPWM control algorithm based on 60° coordinate system are mainly analyzed and simulation comparison is given. Fault-tolerant technique is introduced and theoretical analysis and simulation experiment have carried on for three-level inverter fault-tolerant technique based on the example of short circuit fault.In addition, turbine side converter adopts predictive direct power control strategy.Theoretical derivation and mathematical model are given. This control stragety can obtain the fixed switching frequency, the PI regulator is nonessential,the design parameters is simple and dynamic effect is good; the control strategy which based on direct power control with virtual flux is introduced to the grid connected inverter, use voltage as the outer loop. And the active power and reactive power can be estimated directly using the DC voltage and the switch value, eliminating the need for grid voltage sensors, and enhance the stability of the system.Lastly, based on the theoretical analysis, a MATLAB simulation model and corresponding experiment platform based on TMS320F2812 have been set up. the experimental results have proved that theoretical analysis and control strategy are correct and feasible.