电网谐波条件下双馈感应风电系统改进控制

Improved Control of Doubly Fed Induction Generator Wind Turbine with Series Grid-side Converter under Distorted Grid Voltage Conditions

为提高电网谐波条件下双馈感应发电机DFIG(doubly-fed induction generator)的安全稳定运行性能及系统并网电能质量,利用基于串联网侧变换器的双馈风电系统具有定子机端电压灵活可控的特性,在对含有5、7次谐波电网电压条件下该系统运行行为分析的基础上提出了电网谐波条件下适用于该系统的改进控制策略;在实现发电机电流无畸变,且其输出功率、电磁转矩无波动的同时,亦可实现系统输出功率无6倍频波动或输出电流无畸变2种可选的运行功能;最后,对1台2 MW基于串联网侧变换器的DFIG系统在电网谐波条件下的仿真分析,验证了所提改进控制策略的有效性。

In order to improve the safe and stable operation performance of the generator and power quality under distorted grid voltage conditions, doubly fed induction generator （DFIG） wind power system based on series grid-side converter （SGSC） is adopted in the paper, due to its characteristic of flexible controlled stator voltage of DFIG. Based on analyzing the whole system operational behavior under grid voltage distortion of fifth-order and seventh-order harmonics, the improved control strategies for the DFIG system with SGSC under grid voltage distortion conditions are proposed in this paper. With the propose control strategies, the generator＇s currents without distortion and no oscillations in its output power and electromagnetic torque can be realized simultaneously. In the meanwhile, the two alternative operational functionalities concluding no six times grid frequency pulsations in the total power, or the total current entering the grid without distortion can be nicely achieved. Finally, simulation results of a 2 MW DFIG system with SGSC under distorted grid voltage condition verify the proposed control strategy.