基于变流器联合控制的永磁风电机组孤网调频方法

A Frequency Modulation Method of Wind Turbines With Permanent Magnet Synchronous Generators Based on Combination Control of Converters for Isolated Grids

针对孤网中负荷与分布式电源波动引起的频率骤变及小幅振荡问题,展开永磁风电机组孤网调频研究。基于改进的转矩下垂控制算法,提出一种变流器小信号动态模型,探讨降载系数与下垂系数对机侧变流器输入功率的影响,以及直流母线电压补偿值对网侧变流器输出功率的影响。为抑制风速及负荷扰动,设计基于H_∞理论的联合控制器,给出控制器相关参数,优化变流器输入、输出功率,从而在机组稳定运行前提下提高孤网抗扰动能力,有效减弱频率骤变并抑制小幅振荡。联合控制与其他控制方法仿真分析表明,基于变流器联合控制机组运行数据较稳定,且孤网频率波动最小。最后通过实验进一步验证所提控制策略的有效性。

Aiming at the sudden change and the slight oscillation of frequency caused by fluctuations of loads and distributed generation in isolated grids, researches on frequency modulation of wind turbines with permanent magnet synchronous generators was conducted. A small-signal dynamic model of converters was proposed based on the improved torque droop control algorithm. The effects of the deloading factor, droop factor and DC-link voltage compensation on the generator-side converter input and the grid-side converter output were further studied respectively. In order to inhibit the disturbances of the wind speed and loads, a combination controller was designed based on the H∞ theory, and controller parameters were designed to optimize inputs and outputs of converters. The anti-disturbance capacity in isolated grids was increased to weaken sudden changes and the slight oscillation of frequency. Simulation results and comparison with other control methods show that operation data of wind power generators are relatively stable and the fluctuation of the isolated grid frequency is minimized based on the combination control of converters. The effectiveness of the proposed control strategy is verified through experiments.