The Application Of Dual PWM Converter In Direct-drive Permanent Magnet Wind Power Generation System

With the energy shortage and environmental degradation, wind power as a renewable resource, has been national attention. Because of simple structure, high reliability, no gears and wind energy conversion efficiency is improved, direct-drive wind turbine has been a hot wind-power generation technology.The traditional direct-drive wind turbine each works with a set of pairs of PWM converter, increasing the complexity and the cost of the system. As a starting point, this article proposes a new type of direct-drive permanent magnet wind power generation system model. In the new system, multi-generator use a set of converter. According to the changes of wind speed, the wind farm bus set to a lower frequency, the converter adjusts each generator's frequency, when it is in line with the wind farm bus, generators connect with the grid, converter removed. In this way of connecting with the grid, the frequency of most generators will be higher than the bus frequency,few generators will be lower than the frequency of bus, then by controlling the converter make the power reverse, generators transfer power to the grid or absorb power from the grid, increase speed, when it is in line with the wind farm bus voltage, generators connect with the grid.Control pairs of PWM converter to achieve two-way flow of energy is the main content of this article. This article analyzes the PWM converter model,works, and analyzes its methods and operating mode; Analyzes the working principle of two-way flow of energy; Based on the establishment of the mathematical model of a new system, study the network side and machine-side control strategy,at the machine-side using the zero d-axis rotor current control, at the network side using voltage-oriented control, achieving two-way flow of energy. In the PSCAD simulation environment, presented in this paper the energy of the two-way flow control strategies in direct-drive permanent magnet wind power generation system carried out a simulation study, the results show that this control strategy is right. Use TMS320LF2407A DSP as the core to build the experimental circuit, PWM converter and its control method are carried out under experiment. The experimental results validate the correctness of the designed PWM converter to achieve two-way flow of energy, as well as the theoretical analysis is correct.