结合有源阻尼的风电变流器改进线性自抗扰控制

Improved linear active disturbance rejection control for wind power converter combined with active damping

为提高风电变流器网侧的稳定性,解决负载波动时变流器并网接口的谐波和谐振问题。提出了一种改进的有源阻尼线性自抗扰控制(ADLADRC)策略。首先建立LCL型变流器数学模型,分析传统三阶自抗扰控制器原理。在此基础上,为提高传统观测器的观测能力,设计了在观测器总扰动通道上串联滤波器的改进自抗扰控制,并引入有源阻尼与其结合完成改进ADLADRC控制策略设计。然后通过频域分析法对改进ADLADRC下变流器系统进行频率特性分析可知,改进ADLADRC控制具有更好的并网稳定性和谐波谐振抑制力。最后,通过仿真对比所提控制策略与传统LADRC、传统PI控制下的并网点电流波形。仿真结果显示稳态条件改进ADLADRC满载谐波率相比PI的2.89%降为0.39%和半载谐波率相比PI的7.64%降为0.60%,表明所提控制策略不仅有更好的并网稳定性,还有在负载波动时快速的动态响应和谐波抑制力。

In order to improve the grid-connected stability of wind power converter,the harmonic and resonance problems of the grid-connected interface of the converter are solved when the load fluctuates.This paper presents an improved active damping linear active disturbance rejection control(ADLADRC)strategy.Firstly,the mathematical model of LCL converter is derived.Traditional active disturbance rejection control technology is analyzed.On this basis,to improve the observation ability of traditional observer,an improved active disturbance rejection control based on series filter in the total disturbance channel of the observer is designed.And the introduction of active damping and its combination to complete the improved ADLADRC control strategy design.Then the frequency characteristics of the converter system under the improved ADLADRC are analyzed by frequency domain analysis method.The improved ADLADRC control has better grid-connection stability and harmonic resonance suppression.Finally,through simulation,the proposed control strategy is compared with the current waveform of traditional LADRC and traditional PI control.Under the steady-state condition,the simulation results show that the full-load harmonic rate of the improved ADLADRC is 2.89%lower than that of PI to 0.39%,and the half-load harmonic rate is 7.64%lower than that of PI to 0.60%.It indicates that the proposed control strategy not only has better grid-connected stability,but also has fast dynamic response and harmonic suppression when the load fluctuates.