基于LCL的风电并网逆变器无传感器控制

Study on Voltage Sensor-less Control for Wind Grid Connection Inverter with LCL Filter

基于LCL滤波器的风电并网逆变器(LCL-GCI)需要增加传感器去检测电容电压或者电容电流来抑制LCL滤波器存在的固有谐振问题,提高了系统的控制成本,降低了系统的运行可靠性。鉴于此,在分析虚拟磁链观测思想和LCL-GCI数学模型的基础上,提出了LCL-GCI的无电网和无电容电压传感器控制技术,只检测变换器侧电流和直流母线电压,通过状态重构的方法设计电网电压观测器和LCL电容电压和电流观测器。利用观测器输出的电容电流进行前馈控制,从而实现了LCL-GCI的有源阻尼控制。采用低通滤波器来代替纯积分器来设计观测器,使得系统具有较强的抗干扰、抗负载扰动能力。实验结果表明,LCL-GCI的无传感器控制技术能够减少传感器数量,降低系统的控制成本,具有一定的应用价值。

For the resonance problem of LCL filter,it is needed to increase the number of sensors to detect capacitor voltage or the capacitor current signals,which enhances the control costs and reduces the reliability of the system.In view of this,the core ideal of the virtual flux observing and the mathematical model of LCL-GCI are analyzed and then the sensor-less control technology without grid and capacitor voltage sensors for LCL-GCI is presented.The active damping control of LCL-GCI is realized using the capacitor current feed-forward which is fetched by the LCL capacitor observer in the case of only detecting the converter current and DC-link voltage.In the design of observer,the low-pass filter is used to replace the pure integrator to obtain strong ability of anti-load disturbances.Experimental results show that the voltage sensor-less control technology can observer the grid voltage and capacitor voltage precisely,make the system working steadily and has good anti-disturbance ability,and decrease the numbers of used sensors,reduce the system control cost and has great application values.