摘要
传统PI控制策略下,光伏并网逆变会受到外部干扰、系统稳定性差等因素的影响。基于此,提出了一种改进的双闭环控制策略。光伏发电并网逆变器因其内部存在电感、电容等非线性器件,所以控制难度较大。国家电网中的电流可通过PI控制器将逆变器输出的电流并入,采用非线性自抗扰控制器稳定电压外环直流电母线电压,即采用扩张状态观测器观测一些综合扰动项,如非线性不确定因素和外部干扰,最终确定具有前馈补偿的非线性反馈控制律。仿真结果表明,该方法与双闭环PI控制方法相比能够更好地跟踪目标轨迹,降低了并网电流的总谐波畸变率(THD),且抗干扰性更好。
Under the traditional PI control strategy,PV grid-connected inverter is affected by external interference and poor system stability. Based on this,an improved double closed-loop control strategy is proposed.The grid-connected photovoltaic inverters are difficult to control because of the existence of inductance,capacitance and other non-linear devices inside them. The current in the national grid can be combined with the current output from the inverter through the PI controller. The nonlinear auto-disturbance controller is used to stabilize the voltage external loop DC bus voltage. The state observer observes some integrated disturbance terms,such as nonlinear uncertainties and external disturbances,and finally determines the nonlinear feedback control law with feedforward compensation. The simulation results show that compared with the double closed-loop PI control method,the proposed method can better track the target trajectory and reduce the total harmonic distortion rate(THD) of the grid-connected current,and the anti-interference is better.
作者
李凯晗
LI Kai-han(School of Electrical Engineering,Guangxi University,Nanning 530000,China)
出处
《通信电源技术》
2019年第2期26-27,共2页
Telecom Power Technology
关键词
稳定性
光伏发电并网
逆变器
非线性器件
stability
photovoltaic power generation grid
inverter
nonlinear device
